In an ideal world, emergency personnel have 15 minutes to save a limb after a tourniquet is tied. Asaiante used a pen and wrote down the time on what was left of the man's jeans, so hospital staff would know how many minutes they had left when he arrived. It was shortly before 3 p.m.
The wounded were labeled by number for the ambulances -- 1, 2 and 3 -- 1 being the highest priority.
Segatore had just worked to save a man who had lost both his legs when a woman arrived in critical condition, struggling to breathe.
The father of seven children looked at her face. Her freckles, wide eyes and body type reminded him of his 19-year-old daughter.
"We can't let this young girl die," he kept thinking.
Along with a doctor and emergency medical technician, Segatore scanned her wounds, mostly on the left side of her body. One leg was twisted backwards, and she had a wound near her left hip. She had black markings on her head, possibly residue from being so close to the blast.
She had already been given several minutes of CPR by those who rushed her into the tent. Segatore offered her comforting words before taking over CPR.
I'm a nurse, he told her. You're in a tent at the finish line.
He tried to resuscitate her. They stopped CPR briefly to hook up a heart monitor. The screen showed squiggly lines, but the heart wasn't pumping blood. There was no pulse. The physician said to stop. "We knew what we had," Segatore said.
All at once, a wave of sadness and anger coursed through the three men. In exasperated unison, they shouted, "Fuck!"
"You don't expect them to die of a bomb blast in the middle of your own city," Segatore reflected.
He covered her with a blanket. Eventually, he and a National Guardsman moved her cot to a private area. They worried it might get tipped over or her blanket pulled off.
Even amid the chaos, they thought to give her dignity. "In death, we want people to be as respected as they are in life," he said. "We do that by treating them as we would want to be treated, as if they're our family members."
But there was little time to reflect. The patients kept coming, wave after wave.
Some were so stunned they couldn't speak. They would respond to questions, but their faces were covered with blank stares. Sometimes, they mouthed words but no sound came out.
One man, Ron Brassard, had blood pouring out of a leg. He screamed in pain and yelled, "I'm not going anywhere without my daughter."
He repeated it over and over and over.
More 'Apollo 13' than 'ER'
"There was an explosion at the finish line."
That was the message relayed to Dr. Horacio Hojman, the associate director of trauma and the surgical director of the intensive care unit at Tufts Medical Center.
He and his staff instantly activated the hospital's emergency response plan. Four trauma teams, each consisting of four medical staff -- an ER attendant, two residents and an intern -- scrubbed in. They quickly cleaned the emergency room, wiping everything down, mopping the linoleum floors and preparing the rooms. Patients already there were moved to other parts of the hospital.
In less than 10 minutes they were ready.
Born in Argentina, Hojman had treated patients of mass shootings and explosions in his homeland. He's lived in the United States for more than 20 years and has always preached to his staff about the need to be prepared for worst-case scenarios.
Everyone on his emergency team has gone through what he calls "the simulator" at Tufts medical school to prepare for a moment like this. It's a facility designed just like an ER to teach doctors to keep calm under pressure.
The idea, he said, is to make the training "so difficult that, by comparison, this seems to be easy."