President Obama has visited the bedside of dozens of Boston Marathon bombing victims, including Karen Rand - who lost her best friend in the horrific blasts.
After attending the interfaith service in Boston on Thursday morning, he visited with hospitalized victims still recovering from the devastating twin blasts.
Miss Rand was one of them. She was waiting near the finish line with her best friend Krystle Campbell to cheer on Karen's boyfriend when the first explosion hit.
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Emotional visit: President Obama visited the bedside of Karen Rand- who lost her best friend Krystle Campbell in the Boston Marathon blasts - on Thursday
High-profile visitor: President Obama speaks with the staff at Massachusetts General Hospital, where he visited with victims of the bombing
Krystle was killed in the blast. Karen will survive.
Krystle, a 29-year-old steakhouse manager who went to the race every year, was the second fatal victim to be identified.
Doctors initially told Krystle's father, William Campbell Jr., that his daughter had survived.
But doctors had mistaken her for Karen, because she was carrying Krystle's identification they were unable to correct the mistake while she was in surgery.
Campbell spent 12 hours believing his daughter was alive and only learned the truth after going into the post-operating room and saw Karen lying there instead.
'We had the doctors come out and tell us everything they did [to save Karen] — and it wasn't our daughter,' Campbell said.
Victim: Krystle Campbell's parents had believed she survived for 12 hours and only learned she had died after going into the hospital room and finding Miss Rand instead
Krystle went to marathon, which she did every year, and was with Rand, cheering on Rand’s boyfriend.
They were struck by the first blast as they waited near the finish line.
William Campbell rushed to the hospital and felt relieved when doctors said they were operating on their daughter's leg at Massachusetts General Hospital.
But when nurses brought him into a post-operating room around 2am and saw Rand instead.
'I said, "That’s not my daughter, that’s Karen! Where’s my daughter?" The doctors were as shocked as we were,' Campbell said.
A Boston detective later showed them a photo of Krystle, who worked as a manager at Jimmy's Steakhouse.
'I almost passed out on the floor,' Mr Campbell said as he was about to view his daughter's body.
Heartbreaking. Mother of Boston bombing victim pays tribute to...
Heartbreaking mix-up: William Campbell was told his daughter, Krystle, (right), survived but later discovered doctors were actually operating on her friend Karen Rand (left)
Heartbroken: Krystle's mother Patty Campbell, center, flanked by her brother, John Reilly, and son, Billy, spoke to reporters outside her home in Medford, Massachusetts on Tuesday and said her daughter had a heart of gold
Mourning: Patty Campbell (top right), mother of Boston Marathon explosion victim Krystle Campbell, told reporters that she couldn't have asked for a better daughter
Tragedy: Krystle Campbell worked as a manager at a steakhouse and was living with her ill grandmother so she could take care of her
'She was the best person you’d ever meet. She helped everybody,' Mr Campbell said. 'I don’t care who you were, she was always there.'
Krystle was the second of the victims killed in the two blasts that came just seconds apart. The first victim identified was eight-year-old Martin Richard.
The third was a Boston University student Lu Lingzi, of China.
There were 183 people injured in the attack. As many as 10 people suffered a lost limb, including two children.
Krystle's mother, Patty Campbell, was overwhelmed with grief when she addressed reporters gathered outside her home on in Medford, Massachusetts on Tuesday.
'She had a heart of gold...she was always smiling and friendly,' Patty Campbell said, fighting back tears as she remembered Krystle.
'I couldn't ask for a better daughter. It's hard to believe this is happening. This doesn't make any sense.'
Krystle's grandmother Lillian Campbell said she went to the marathon every year 'because she loved people'
'She was the best,' the mother said.
'She’s been doing it since she was a little girl,' said her grandmother, Lillian Campbell. 'She didn’t miss a Marathon, watching it at the finish line.
'She enjoyed doing it because she liked people. She’d meet a lot of people over there. She was very friendly, Krystle. She'd talk to anybody.'
Her grandmother added that Krystle had just moved to the town a short time ago.
She was living with her grandmother to care for her during an illness for the past couple of years.
Lillian said that her granddaughter 'was just beautiful.
'She was fun, outgoing person. She was always there to help somebody. All her friends loved her.
'The family is besides themselves now because something happened to her,' the grandmother said.
Martin Richard, 8, from Dorchester, Massachusetts was among the three people killed
Tragic: The third victim of the blast was identified as Boston University graduate student Lu Lingzi, 23, of China