The deadliest prison fire the world has seen in a century claimed 358 lives in an overcrowded Honduran jail, officials said Wednesday.

The jail in the Comayagua province was at double capacity with 856 prisoners when the blaze broke out around midnight Tuesday, said lead investigator and Supreme Court Justice Richard Ordonez.

The fire started when an unidentified prisoner set his mattress ablaze. Comayagua governor Paola Castro, who was once a prison employee, said the inmate called her moments before the fire started and screamed: "I will set this place on fire and we are all going to die!"

She called for help immediately, but firefighters said they were kept outside for half an hour by guards who fired guns in the air, thinking the prisoners were rioting.

It's believed that some 475 inmates escaped during the fire. Lucy Marder, head of forensic services in the town of Comayagua, told reporters the prison housed people convicted of serious crimes, such as murder and robbery.

Comayagua fire department spokesman Josue Garcia said he saw "hellish" scenes while trying to put out the fire.

Garcia said many prisoners were trapped because the guards who had the keys to their cells could not be found in time. Some bodies were found fused together.

Marder said 21 injured people were taken to hospital as she warned that the death toll could rise.

Local reports say the prison, which is surrounded by farm fields, was completely destroyed by the blaze.

Angry relatives of the dead inmates tried to storm the gates of the prison Wednesday morning to recover the remains, witnesses told The Associated Press, but the crowds were driven back by police firing tear gas.

A local TV station showed images of dozens of relatives hurling rocks at officers.

"We want to see the body," shouted Juan Martinez, whose son was reported dead. "We'll be here until we get to do that."

Survivor Ever Lopez, 24, who was serving time for homicide, said he was sleeping when the fire broke out.

"I saw the smoke from cell block 6 and it spread throughout the prison," he said. "The other prisoners and I broke through the roof with our bare hands and fled. Thank God I'm alive."

Marder said it would take months to identify victims since some were burned beyond recognition, adding that DNA tests would be required in some cases.

According to the United Nations, Honduras has one of the highest murder rates in the world.

Local journalist Evangelina Varquero told CTV News Channel that many of the prisons in the country of 7.6 million are overcrowded.

"We have 24 prisons here with a capacity of 8,000 inmates, but the real number is 13,000. As an example, the prison in Comayagua… has a capacity for 450, but the real number of inmates inside was 800 or so -- so about twice the capacity," she said from Tegucigalpa.

Government officials have repeatedly promised to improve conditions, but human rights groups say little has been done.

Honduran President Porfirio Lobo said on national television that he had suspended the country's top penal officials and said he would request international assistance in carrying out a thorough and transparent investigation.

"This is a day of profound sadness," he said.

In 2004, a fire killed more than 100 gang members in a badly overcrowded prison in San Pedro Sula, Honduras. That fire was thought to have been caused by an electrical short circuit on a refrigerator.

A year earlier, 68 people, including guards and visitors, died in a violent clash between gang members at a ramshackle jail at El Porvenir, on Honduras's north coast.

With reports from the Associated Press