The ER was already busy, close to full - gunshots, car wrecks, strokes - when the "get ready" call came in at 9:45 p.m.
By 10:30, they began arriving by police car, ambulance, anything.
By midnight, 54 had made it to Temple University Hospital, which treated more passengers from Amtrak's Tuesday night disaster than any other emergency room.
The most critical patients were rushed into one of the three trauma bays just inside the ER door. Teams of doctors and nurses were assigned to each bay, responsible for stabilizing patients and moving them through with skill and speed, making room for the next.
Lucas Ferrer, the chief resident on the trauma team - his 24-hour shift had started at 6 a.m. - recalled a patient who was disoriented and having trouble breathing.
Three teams were immediately at his side - an emergency doctor to intubate, a respiratory therapist to hook him to the ventilator, and Ferrer, a surgeon, to cut.
"From somebody that was in a lot of distress," Ferrer said, "he was so stable, and it was so quick, just as we had been trained."
That patient was moved on, and the next one brought in.
"It was amazing," Ferrer continued. "Just the way we all worked together so smoothly. Everybody knew what each other's capabilities were and trusted each other."
Staff were clearing beds, moving people to other wings, some discharged early. Twenty gurneys were lined up in the ambulance bays outside. A hospital is all about flow.
Declaration of a Level 4 emergency - the highest - had triggered automatic text messages to doctors and nurses from radiology, anesthesiology, general surgery, pathology. Extra food service workers opened the cafeteria and walked a cart with Gatorade and water around the ER all night, hydrating staff and patients alike.
Ernest Yeh, an emergency-room doctor on duty that night and a member of the hospital's emergency preparedness team, said the staff drill and prepare for such mass casualties, and the preparedness paid off. But it is the intangibles that really stand out, the cooperation and communication, the fluid movement of staff and patient, intrinsic, intuitive - what many at Temple called organized chaos.
Yeh said he would remember the little things, the unselfishness - a doctor cleaning a bed to make space, a supervisor holding a patient's hand.
Particularly memorable to him was the gratitude of the patients, and their generosity. He often heard them say: "Don't take care of me, take care of the next person," or, "I'm OK. I can wait," even when they were suffering from significant injuries.
Most of the injuries were broken arms, legs, and ribs, along with several cracked vertebra. But there was no spinal injury serious enough to cause paralysis. Only one patient died. (Most fatalities were at the scene.)
Jim Gaines, 48, from Plainsboro, N.J., came in with a massive chest injury. Temple's chief medical officer, Herbert Cushing, said he believed that Gaines was in a front car, and that doctors restarted his heart twice but couldn't a third time.
Six patients were still in critical condition at Temple on Thursday, most of them with severe chest injuries, Cushing said, although he expected all of them to have "good outcomes."
Like many other nurses, Gia Shepherd, 25, an emergency-room nurse, had worked all day, gone home at 7, but when she saw the news that night, drove back to the hospital from her home in Northeast Philadelphia. Her adrenaline was pumping.
"I'm not going to sleep anyway," she reasoned. "I might as well come in."