He arrived at the beginning of a three-hour standoff. Officer Delgado dragged some of the wounded to safety and took cover behind a wall.

Officer Delgado recounted a harrowing night of watching club patrons trip over corpses and writhe in agony as their bullet-ridden bodies were pulled across broken glass. The image of Brenda Lee Marquez McCool, with her shock of cropped white hair and tattoos, haunts him. He is among the group of responders who are likely to require counseling to find the will to return to work.

Officer James Hyland of the Orlando police is another. Officer Hyland, who did two tours in Afghanistan, said what he saw at Pulse was worse. “It makes me forget about a lot of the stuff that happened in the military,” he said. “The situation was worse than being in a war zone.”

At a debriefing held at a local high school shortly after the shooting, many officers sat and cried, said Joseph Imburgio, one of the Orlando police officers who was on the scene at Pulse.