Authorities investigating the Boston Marathon blasts that killed three and injured more than 175 believe the two bombs were assembled from household pressure cookers, a crude but effective explosive that has been thwarted in prior U.S. terror plots.
Authorities found a pressure-cooker lid believed to have been part of a bomb that apparently was catapulted onto the roof of a nearby building, a person briefed on the investigation said Wednesday. A small piece of a circuit board they suspect was part of one of the explosive devices also was found at the scene, the person said.
Investigators are exploring whether the bombs were assembled not far from the scene of Monday's horrific explosions since transporting such improvised devices over any significant distance could trigger a premature detonation, according to a law-enforcement official with knowledge of the matter.
Working with local police, federal agents are canvassing Boston hotels and short-term rentals for clues on where the bombs could have been constructed, the official said.
More than 24 hours after the attacks, no one had claimed responsibility and no suspect had been identified.
Federal Bureau of Investigation agents, with the assistance of U.S. Customs and Border Protection personnel, have been scrutinizing passenger lists from flights that had recently arrived at Boston's Logan Airport for clues, the official said.
Among the injured, more than 20 were in critical condition, hospitals said. Thirteen people had to have limbs amputated.
The blasts killed 8-year-old Martin Richard of Boston's Dorchester section, whose mother and sister were seriously injured; 29-year-old Krystle Campbell, a restaurant manager from Medford, Mass.; and Boston University graduate student Lu Lingzi, a Chinese citizen.
Celeste Corcoran, who was at the race to cheer on her sister, Carmen Acabbo, was one of many victims whose limbs were amputated. The 47-year-old hairdresser from Lowell, Mass., lost both legs, and her 18-year-old daughter, Sydney, was grievously injured.
But when Ms. Corcoran came out of surgery Monday night, her first thought, Ms. Acabbo said, "was that she was so mad she didn't get to see me finish."
Ms. Acabbo responded: "I finished my marathon and now I'm going to run yours with you, every step of the way."
The materials believed to have been used in the bombs closely match those that Naser Jason Abdo, a young Texas soldier, had amassed before he was charged by the FBI in Texas in 2011 with plotting to attack fellow soldiers.
An FBI expert testified at his trial that it would have taken about 30 minutes to build a bomb using materials Mr. Abdo had gathered—including a pressure cooker, gunpowder, clocks and electrical tape—by following instructions in an al Qaeda magazine found in his backpack.
Mr. Abdo was convicted and is serving life in prison.
In the foiled Times Square bombing of 2010, authorities said one of the three devices would-be bomber Faisal Shahzad had assembled was a pressure cooker containing more than 100 firecrackers.
The Boston investigation, led by the FBI, intensified Tuesday, with authorities interviewing witnesses and examining what one official called the "most complex crime scene" the city had ever dealt with.
Hundreds of federal and local investigators began to slog through a vast trove of videos, photos, local hotel manifests and other potential evidence to determine how bombs could have been placed in an area that had been swept for explosives by bomb-sniffing dogs, said people familiar with the investigation.
Boston FBI chief Richard DesLauriers said investigators would go to the "ends of the earth" to find those involved in the attack and that "the range of suspects remains wide open." More than 2,000 people called in tips to the FBI, he said.
"This will be a world-wide investigation," he said.
The bombs appeared to have been built by packing the pressure cookers with a black powder explosive as well as nails and pellets to maximize casualties, a lawmaker briefed by investigators said.
The bombs were placed in black bags or backpacks, the FBI said; fragments of BBs, nails and shreds of black nylon from the bags were found at the site of the bombings.
U.S. counterterrorism officials have warned for a decade about the use of pressure cookers to manufacture bombs. The warnings came after finding such bomb-making was being taught at terrorist camps in Afghanistan.
Terror in the U.S.
Officials Tuesday cautioned that this type of bomb could have been made by any number of groups or individuals.
"We have been very good, very lucky since 9/11," said Pete Ahearn, a former FBI official who investigated a 2002 al Qaeda plot in Buffalo, N.Y.
He said that since the Sept. 11, 2001, attacks, al Qaeda has moved more to inspire plots because its ability to direct attacks has been curbed by U.S. counterterrorism efforts.
Officials familiar with the probe said all possible scenarios were being pursued by investigators.
They said they had not detected chatter about the attacks by foreign terror groups such as al Qaeda or other common indicators of foreign involvement. The Pakistani Taliban went so far as to put out a public statement saying the group had no role in the Boston attack.
Such a lack of chatter could indicate either a sophisticated small operation or a homegrown radicalized attacker, said Rep. Michael McCaul (R., Texas), chairman of the House homeland security committee, who was briefed by investigators. Mr. McCaul added that it was too early to draw conclusions.
President Barack Obama in a brief statement Tuesday called the bombings an act of terrorism, describing the incident as a "heinous and cowardly act."
As deadly as the back-to-back blasts were, one reason more lives weren't lost was the rapid and well-coordinated response by police and emergency responders drilled in mass-casualty events.
Volunteers also helped quickly triage the wounded, wrap tourniquets around bloodied and severed limbs and wheel them to a big medical tent near the finish line that had been set up to treat injured and dehydrated runners and was staffed by emergency-room doctors from around the city.
"There was a lot of lifesaving work done at the scene," said Boston Health Commissioner Barbara Ferrer.
More than 30 ambulances descended on the scene and transported the injured to 11 area hospitals—including some of the world's top medical centers.
The first victims began arriving at emergency rooms across the city within 10 minutes of the blasts.
Al Qaeda terrorists have used the Internet to promote homemade devices.
In 2010, the Yemen-based al Qaeda in the Arabian Peninsula's Internet magazine carried an article with a step-by-step guide that included the use of a pressure cooker.
The article, headlined "Make a Bomb in the Kitchen of Your Mom," listed common items including filaments from Christmas light bulbs, gunpowder and a clock.
The idea was to avoid buying chemicals and explosive precursors that are tracked by authorities "so as not to arouse suspicion," the article said.
In a 2004 law enforcement alert, the Department of Homeland Security said: "Pressure-cooker bombs are made with readily available materials and can be as simple or as complex as the builder decides. These types of devices can be initiated using simple electronic components including, but not limited to, digital watches, garage door openers, cellphones or pagers. As a common cooking utensil, the pressure cooker is often overlooked when searching vehicles, residences or merchandise crossing the U.S. borders."
Dan Defenbaugh, a former FBI bomb technician who led the investigation of the Oklahoma City bombing, cautioned that while al Qaeda has promoted the use of pressure cookers to build bombs, one shouldn't assume the bomber is necessarily an al Qaeda follower.
The pressure cooker's history as a bomb canister reaches back decades, he said.
Pressure cookers, he said, help build up pressure when using "low explosives"—those less powerful than a more sophisticated explosive like C-4.
Authorities found a pressure-cooker lid believed to have been part of a bomb that apparently was catapulted onto the roof of a nearby building, a person briefed on the investigation said Wednesday. A small piece of a circuit board they suspect was part of one of the explosive devices also was found at the scene, the person said.
Investigators are exploring whether the bombs were assembled not far from the scene of Monday's horrific explosions since transporting such improvised devices over any significant distance could trigger a premature detonation, according to a law-enforcement official with knowledge of the matter.
Working with local police, federal agents are canvassing Boston hotels and short-term rentals for clues on where the bombs could have been constructed, the official said.
More than 24 hours after the attacks, no one had claimed responsibility and no suspect had been identified.
Federal Bureau of Investigation agents, with the assistance of U.S. Customs and Border Protection personnel, have been scrutinizing passenger lists from flights that had recently arrived at Boston's Logan Airport for clues, the official said.
Among the injured, more than 20 were in critical condition, hospitals said. Thirteen people had to have limbs amputated.
The blasts killed 8-year-old Martin Richard of Boston's Dorchester section, whose mother and sister were seriously injured; 29-year-old Krystle Campbell, a restaurant manager from Medford, Mass.; and Boston University graduate student Lu Lingzi, a Chinese citizen.
Celeste Corcoran, who was at the race to cheer on her sister, Carmen Acabbo, was one of many victims whose limbs were amputated. The 47-year-old hairdresser from Lowell, Mass., lost both legs, and her 18-year-old daughter, Sydney, was grievously injured.
But when Ms. Corcoran came out of surgery Monday night, her first thought, Ms. Acabbo said, "was that she was so mad she didn't get to see me finish."
Ms. Acabbo responded: "I finished my marathon and now I'm going to run yours with you, every step of the way."
The materials believed to have been used in the bombs closely match those that Naser Jason Abdo, a young Texas soldier, had amassed before he was charged by the FBI in Texas in 2011 with plotting to attack fellow soldiers.
An FBI expert testified at his trial that it would have taken about 30 minutes to build a bomb using materials Mr. Abdo had gathered—including a pressure cooker, gunpowder, clocks and electrical tape—by following instructions in an al Qaeda magazine found in his backpack.
Mr. Abdo was convicted and is serving life in prison.
In the foiled Times Square bombing of 2010, authorities said one of the three devices would-be bomber Faisal Shahzad had assembled was a pressure cooker containing more than 100 firecrackers.
The Boston investigation, led by the FBI, intensified Tuesday, with authorities interviewing witnesses and examining what one official called the "most complex crime scene" the city had ever dealt with.
Hundreds of federal and local investigators began to slog through a vast trove of videos, photos, local hotel manifests and other potential evidence to determine how bombs could have been placed in an area that had been swept for explosives by bomb-sniffing dogs, said people familiar with the investigation.
Boston FBI chief Richard DesLauriers said investigators would go to the "ends of the earth" to find those involved in the attack and that "the range of suspects remains wide open." More than 2,000 people called in tips to the FBI, he said.
"This will be a world-wide investigation," he said.
The bombs appeared to have been built by packing the pressure cookers with a black powder explosive as well as nails and pellets to maximize casualties, a lawmaker briefed by investigators said.
The bombs were placed in black bags or backpacks, the FBI said; fragments of BBs, nails and shreds of black nylon from the bags were found at the site of the bombings.
U.S. counterterrorism officials have warned for a decade about the use of pressure cookers to manufacture bombs. The warnings came after finding such bomb-making was being taught at terrorist camps in Afghanistan.
Terror in the U.S.
Officials Tuesday cautioned that this type of bomb could have been made by any number of groups or individuals.
"We have been very good, very lucky since 9/11," said Pete Ahearn, a former FBI official who investigated a 2002 al Qaeda plot in Buffalo, N.Y.
He said that since the Sept. 11, 2001, attacks, al Qaeda has moved more to inspire plots because its ability to direct attacks has been curbed by U.S. counterterrorism efforts.
Officials familiar with the probe said all possible scenarios were being pursued by investigators.
They said they had not detected chatter about the attacks by foreign terror groups such as al Qaeda or other common indicators of foreign involvement. The Pakistani Taliban went so far as to put out a public statement saying the group had no role in the Boston attack.
Such a lack of chatter could indicate either a sophisticated small operation or a homegrown radicalized attacker, said Rep. Michael McCaul (R., Texas), chairman of the House homeland security committee, who was briefed by investigators. Mr. McCaul added that it was too early to draw conclusions.
President Barack Obama in a brief statement Tuesday called the bombings an act of terrorism, describing the incident as a "heinous and cowardly act."
As deadly as the back-to-back blasts were, one reason more lives weren't lost was the rapid and well-coordinated response by police and emergency responders drilled in mass-casualty events.
Volunteers also helped quickly triage the wounded, wrap tourniquets around bloodied and severed limbs and wheel them to a big medical tent near the finish line that had been set up to treat injured and dehydrated runners and was staffed by emergency-room doctors from around the city.
"There was a lot of lifesaving work done at the scene," said Boston Health Commissioner Barbara Ferrer.
More than 30 ambulances descended on the scene and transported the injured to 11 area hospitals—including some of the world's top medical centers.
The first victims began arriving at emergency rooms across the city within 10 minutes of the blasts.
Al Qaeda terrorists have used the Internet to promote homemade devices.
In 2010, the Yemen-based al Qaeda in the Arabian Peninsula's Internet magazine carried an article with a step-by-step guide that included the use of a pressure cooker.
The article, headlined "Make a Bomb in the Kitchen of Your Mom," listed common items including filaments from Christmas light bulbs, gunpowder and a clock.
The idea was to avoid buying chemicals and explosive precursors that are tracked by authorities "so as not to arouse suspicion," the article said.
In a 2004 law enforcement alert, the Department of Homeland Security said: "Pressure-cooker bombs are made with readily available materials and can be as simple or as complex as the builder decides. These types of devices can be initiated using simple electronic components including, but not limited to, digital watches, garage door openers, cellphones or pagers. As a common cooking utensil, the pressure cooker is often overlooked when searching vehicles, residences or merchandise crossing the U.S. borders."
Dan Defenbaugh, a former FBI bomb technician who led the investigation of the Oklahoma City bombing, cautioned that while al Qaeda has promoted the use of pressure cookers to build bombs, one shouldn't assume the bomber is necessarily an al Qaeda follower.
The pressure cooker's history as a bomb canister reaches back decades, he said.
Pressure cookers, he said, help build up pressure when using "low explosives"—those less powerful than a more sophisticated explosive like C-4.