PENSACOLA, Fla. — An apparent gas explosion rocked a jail in the Florida Panhandle late Wednesday, killing two inmates, injuring more than 100 people, and causing the building to partially collapse, according to county officials.

The jail is almost completely destroyed, Escambia County Sheriff David Morgan said at a news conference Thursday morning. Three inmates were unaccounted for, and one corrections officer was seriously injured, he said.

At the blast site Thursday morning, firefighters were entering the building. Pieces of glass and brick were strewn about on the ground. The front of the building appeared bowed out, with cracks throughout. Authorities blocked off roads leading to the jail.

“I ain’t never heard anything like it,” said Rodney Cozine, standing outside his neighboring home, looking at a large gash in the building and piles of debris.

The explosion happened about 11 p.m. CDT at a booking facility at the Escambia County Jail, and as many as 150 inmate and corrections officers were injured, county spokeswoman Kathleen Castro said.

A couple of blocks from the jail, Ellis Robinson and his family awoke to a loud noise sometime after midnight, their home rattling. “It shook the whole house,” he said. “I got up, the dog started barking, people were running up there.” He spent the night observing the chaos and watching as inmates were loaded into buses.

About 600 inmates — 200 men and 400 women — were in the building at the time, Castro said. Those with injuries were taken to hospitals and the uninjured to jails in neighboring counties, officials said. Castro said authorities did not yet know the extent of injuries, but local hospitals said some with minor issues had already been released.

One inmate was pregnant, and she was OK after the blast, Castro said.

The Pensacola area was drenched by rains and severely flooded Wednesday as part of a large storm system making its way across the U.S., and Castro said the building was affected. But she said officials did not yet know whether the flooding and explosion were directly related. The generator was running at the time of the blast, but Castro said officials don’t believe that was related.

Investigators were on the scene. Castro said the fire marshal would ultimately determine the cause.

The names of the two inmates killed in the explosion weren’t immediately released.

Defense attorney Gene Mitchell stood outside police tape at the jail Thursday morning, reviewing dozens of text messages from clients’ relatives wondering what happened to their loved ones.

“I have over 20 clients in there,” he said. “I’ve had dozens of calls. Every other call is a family member wanting to know what has happened to a loved one.”