Columbine by Dave Cullen:
Officers were nearly as confused as TV viewers. Outside, they could hear the blasts. But once they entered, they couldn’t even hear one another. The fire alarm drowned out everything. Communication was limited to hand signals. “Had we heard gunfire and screaming, we would have gone right to that,” a SWAT officer explained.
The barrage of noise and strobe lights beat down their psyches like psychological warfare. Officers could not locate anyone with the alarm code to shut it down. They found an assistant principal, but she was so frazzled she couldn’t remember the digits.In desperation, officers tried to bat the alarm speakers off the walls. One tried to disable the control panel by smashing the glass cover with his rifle butt. The alarms and sprinklers continued until 4:04 P.M. The strobe light that flashed with the alarm continued for weeks.