COMAYAGUA, Honduras -- Anatomy of a tragedy: The only police officer with keys to every cell had a panic attack and ran off after the fire broke out. Fire crews, some as close as a five-minute drive, were called nearly 20 minutes after the first flames were spotted. And once they arrived, they remained outside for several critical minutes after hearing gunshots from the watch towers — intermixed with the screams of dying inmates.

Now, human rights advocates and the relatives of the more than 350 inmates who died in a Tuesday night fire say the deaths were unnecessary and blame the negligence of staff at this prison in northern Honduras.

“What we can definitely say is that these deaths could have been avoided if the cells had simply been unlocked,” said Andres Pavon, president of the Honduran Committee for the Defense of Human Rights. “We’ve found negligence here.”

New details emerged on Thursday about what’s considered one of the worst prison fires in history, a horrific scene where correctional officers began shooting into the air, stayed frozen in their posts, some ran off — bolting past desperate inmates begging for their lives — and the heroics were left to some prisoners.

Fire department commanders and firefighters told El Nuevo Herald they did not receive an emergency call until 10:59 p.m. Tuesday, nearly 20 minutes after the flames began. Three fire trucks plus an ambulance pulled up to the entrance of a long gravel driveway leading the yellow and grey prison complex. Flames a foot high were visible through corrugated metal roof.

Then they waited outside the gates to avoid the gunfire from four police officers in separate watch towers.

“When I got here, just minutes after I found out about the fire, the fire crews were also out here, waiting outside the front gate,” said Laura Yanet, who was still waiting late Thursday to learn whether her brother-in-law had survived. “By the time they got through the gates, everything had already burned.”

Police officers have denied they shot directly at prisoners, as some survivors had told reporters. Fidel Tejeda, an officer who was stationed in one of the watch towers Tuesday night, said he and the others aimed their guns away from the prison buildings and toward the fields that surround the property.

“We were sounding the alarms, the way we’re supposed to during fires and escapes,” said Tejeda, who has worked at the prison for 14 years.

But authorities said there was no working plan for how to deal with fires at the Comayagua prison, considered a model prison because inmates, all minimum-security, perform agricultural work and care for livestock here. And plan or no plan, the place was overcrowded: More than 830 prisoners were housed there when the fire broke out even though the buildings are supposed to house less than 500.

Tejeda said he and his companions couldn’t leave their watch towers to help the inmates, who screamed for somebody to unlock the doors of the 10 buildings that make up the prison.

“It’s against police code to abandon watch,” Tejeda explained.

And so, a mere three officers were on the grounds and only one of them had the keys. A final police officer — bringing the total to eight — watched the entrance to the prison, which sits on the outskirts of this city of about 110,000 people.