It was a disaster waiting to happen.
At 10 a.m. Saturday - as scheduled - a startling bang and a few puffs of multicolored smoke kicked off a carefully planned emergency-preparedness exercise at Philadelphia International Airport.
Strewn across the runway were more than 100 volunteer victims and an American Airlines jet.
"I can't feel my leg!" one victim called out.
The live drill, required every three years by the Federal Aviation Administration, had begun.
As the airport's Engine 78 arrived first on scene, the air-traffic control tower declared a major aircraft incident at the highest level. Additional Philadelphia fire and police units were called in; the large number of victims led to activation of a statewide system. Minutes later, units from other counties began arriving.
"In an actual event, we would respond . . . and then we would get help from the Philadelphia Fire Department and Delaware County, and they are here," said Patrick Sweeney, the battalion chief who heads the airport's fire response. "An incident like this would be tragic, and it's regional. . . . It would really be big in the region, it would be bigger than what you're seeing here today."
For Saturday's exercise, more than 150 firefighters, paramedics, and other first responders worked to triage victims, evaluating their conditions and transporting them to hospitals by ambulance and, for the worst-injured, by two helicopters.
"This guy right here, he's a red," one firefighter called out, reading off the tag given to a victim and attracting the attention of others, who helped load the volunteer onto a cardboard backboard.
Victims with red tags - life-threatening injuries or the potential to get worse - were given first priority, taken on stretchers to a treatment area where paramedics took notes on tags and prepared them for transport to hospitals.
Red tags were everywhere in Saturday's drill.
"We got two more reds coming," a firefighter shouted, as paramedics moved to respond.
As they worked, official evaluators walked the scene, taking notes for later debriefing. The evaluators, a group of aviation professionals, will help airport administrators and agency officials improve.
Evaluations will be compiled in a week or two, airport officials said.
"These practical exercises are valuable because we actually have all the people and the equipment out here," Sweeney said. "We'll respond as we've been trained to respond, and then afterward we'll review it and find out what went right and what went wrong, and we'll adjust."