There was no immediate word from officials about fatalities or the severity of the explosion at the West Fertilizer plant, as Texas Gov. Rick Perry said state officials were also waiting for details about the extent of the damage.
Glenn A. Robinson, chief executive of Hillcrest Baptist Medical Center in Waco, told CNN that his hospital had received 66 injured people, including 38 who were seriously hurt. He said the injuries included blast injuries, orthopedic injuries, large wounds and a lot of lacerations and cuts. The hospital has set up a hotline for families of the victims to get information, he said.
The blast was reported at about 8 p.m. local time (9 p.m. Eastern) in West, a town of about 2,700 people about 80 miles south of Dallas and 20 miles north of Waco.
A spokesman for the Texas Department of Public Safety, D.L. Wilson, said the blast had resulted in "probably hundreds of casualties," adding he didn't know if any of those were fatalities. He said that a nearby nursing home collapsed from the explosion and that people were believed to be trapped inside.
American Red Cross crews from across Texas were being sent to the site, the group said.
Aerial footage showed fires still smoldering in the ruins of the plant and in several surrounding buildings, and people being treated for injuries on the flood-lit local football field, which had been turned into a staging area for emergency responders.
A column of smoke rises after an explosion at a fertilizer plant north of Waco, Texas.
The explosion knocked out power to many local customers and could be heard and felt for miles around.
Lydia Zimmerman told television station KWTX that she, her husband and daughter were in their garden in Bynum, 13 miles from West, when they heard multiple blasts. "It sounded like three bombs going off very close to us," she said.
Brad Smith, who lives 45 miles north of West in Waxahachie, told KWTX that he and his wife heard what sounded like a thunderclap.
Gayle Scarbrough, a spokeswoman for the Department of Public Safety in Waco, told television station KWTX that DPS troopers have been transporting the injured to hospitals in their patrol cars. She said six helicopters were also en route.
KWTX reported the explosion at the West Fertilizer plant was reported at around 7:50 p.m. in a call from the scene.