On September 11, 2001, thousands of New York City firefighters, police officers, and medical workers responded to the fast-developing emergency that took place when terrorists crashed airliners into the two World Trade Center towers. Two hundred units of firefighting companies from all over the city sent trucks and equipment. Senior fire department officials set up a command post near the fire control panels in the first-floor lobby of WTC-1, the first building hit. Some five hundred firefighters began the arduous task of lugging tons of equipment up the eighty floors to try to fight the raging fires. The oxygen tanks, hoses, axes, and other tools burdened many with more than sixty pounds of extra weight.

Policemen on the ground and in the building lobbies helped to clear the surrounding area and evacuate occupants. Paramedics and other emergency medical workers treated hundreds of people who...