CARACAS, Venezuela (AP) — A showdown between armed inmates and guards in an overcrowded cellblock of a Venezuelan jail Friday left at least 29 prisoners dead, an official said.

The clash started when inmates, many armed, refused to let authorities enter, fearing they would be robbed, said Humberto Prado of the Venezuelan Prison Observatory. He said there were reports of at least one explosion.

An official in the Attorney General's office who spoke on condition of anonymity because they were not authorized to speak said at least 29 people were killed and 19 others injured.

Prado called on authorities who run Venezuela's prisons to stop the violent deaths, saying more than 130 inmates have died since 2017 in three separate riots across the country.

"We have this situation because those responsible are converting these cells into dungeons," Prado said in a video posted on Twitter. "Prisoners in Venezuela will continue to die unless something is done."

The prison is in the central state of Portuguesa, some 220 miles (350 kilometers) from the capital of Caracas. It's designed to hold 250, but bulges with 540 inmates, he said.

Last year, a prison riot in the city of Valencia left 68 inmates dead, many of whom were burned alive. At least 39 died two years ago inside a jail in the state of Amazonas, the prisoner rights group said.

Venezuela is in the throes of a historic political and social crisis marked by shortages of food and medicine that's driving millions to flee the country.

Critics say about 30 prisons spread across Venezuela are severely overcrowded, housing 57,000 inmates. They're often run by gangs that traffic drugs and weapons.