A total of 68 people died during an attempted jailbreak in Venezuela after a fire engulfed police holding cells in one of the worst tragedies in years in a notoriously violent and overcrowded prison system.

Attorney General Tarek William Saab gave the death toll in the pre-dawn mayhem at the police headquarters in northern Carabobo state, blaming a fire thought to have been started deliberately.

Carlos Nieto, head of a prisoners’ rights group called Una Ventana a la Libertad (A Window on Freedom), said that some prisoners burned to death and others choked after setting fire to mattresses and stealing a guard’s gun in an attempt to break out.

The dead included two women who were visiting the jail, the attorney general said, adding that four prosecutors have been named to investigate.

Photos taken by Nieto’s group showed the body of a man with burns and firefighters trying to put out flames.

Relatives of those being kept in the detention center tried to force their way in. After one officer was injured by a tossed stone, the crowd was dispersed by police firing tear gas.

A video posted on Twitter showed dozens of people demanding information in front of police guarding the site. Women were seen crying.

“I am a desperate mother. My son has been here a week. They have not given any information,” Dora Blanco told local media.

Local news correspondents wrote on Twitter that the facility was tense Wednesday night.