A fire started by an inmate tore through a severely overcrowded Honduran prison, burning and suffocating inmates in their locked cells and killing as many as 356 people in one of the world's deadliest prison fires in a century, authorities said Wednesday.

Survivors told investigators that an unidentified inmate screamed "We will all die here!" as he lit fire to his bedding late Tuesday night in the prison in the central town of Comayagua.

The lockup housed people convicted of serious crimes such as homicide and armed robbery.

The blaze spread within minutes, killing about 100 inmates in their cells as firefighters struggled to find officials who had keys, Comayagua fire department spokesman Josue Garcia said.

"We couldn't get them out because we didn't have the keys and couldn't find the guards who had them," Garcia said.

Others prisoners were set free by guards but died from the flames or smoke as they tried to flee into the fields surrounding the facility, where prisoners convicted of crimes grow corn and beans on a state-run farm. Rescuers carried shirtless, semi-conscious prisoners from the facility by their arms and legs. One hauled a victim away from the fire by piggyback.

A prisoner identified as Silverio Aguilar told HRN Radio that he first knew something was wrong when he heard a scream of "Fire! fire!"

"For a while, nobody listened. But after a few minutes, which seemed like an eternity, a guard appeared with keys and let us out," he said.

He said there had been 60 prisoners packed into his cell.

Soldiers clashed with the inmates’ relatives who tried to storm the gates Wednesday following the prison fire that killed more than 300 prisoners. (Fernando Antonio/Associated Press)

Some 475 people escaped and 356 are missing and presumed dead, said Hector Ivan Mejia, a spokesman for the Honduras Security Ministry. He said 21 people had been injured.

Honduras has one of the world's highest rates of violent crime, and its overcrowded and dilapidated prisons have been hit by a string of deadly riots and fires in recent years. Officials have repeatedly pledged to improve conditions, only to say they don't have sufficient funds.

According to government statistics, the Comayagua prison was built in the 1940s for 400 people but held more than 800 prisoners watched over by about 100 guards.

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.

Relatives storm the gates

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

Channel 5 television showed dozens of inmates' relatives hurling rocks at officers.

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

The prison housed people convicted of serious crimes such as murder, Danilo Orellana, director of the national prison system, told The Associated Press. The convicts are allowed to work outside, however, unlike those held in a maximum-security facility for the most dangerous prisoners in the capital.

Inmates' relatives stood at the gates of the prison in Comayagua after a fire swept through the prison early Wednesday. (Fernando Antonio/Associated Press)

It sits in the middle of irrigated fields and several large ponds, and appears to be comprised of eight buildings set closely together. Beyond the fields are the city streets of the town of Comayagua. A single dirt, treelined road leads in, passing a soccer field on the property. There is an open, dirt prison yard within the central compound.

A few blocks from the prison, Comayagua bustles with fast-food restaurants, hotels and gas stations.

Fire officials said the fire started around 10:50 p.m. Tuesday when the inmate set his bedding alight.

"Some of his cellmates said that he screamed: 'We will all die here!' And in five minutes everything burned," Orellana said. He did not identify the man or speculate about his motivation. Leonel Silva, fire chief in Comayagua, a town 140 kilometres north of the capital, confirmed Orellana's account to reporters on the scene.

A 2004 prison fire killed more than 100 incarcerated gang members in a state prison north of the Honduran capital. A fire a year earlier at a nearby facility killed 70 gang members. In 1994, a fire sparked by an overheated refrigerator motor in an overcrowded Honduras prison killed 103 people.

Honduran authorities have repeatedly pledged to improve conditions but human rights groups say little has been done in the country of 7.6 million people, a major transit route for drugs headed from South America to the United States.

The U.S. State Department has criticized Honduras for "harsh prison conditions" and violence against detainees. A 1930 prison fire in Ohio killed at least 320 prisoners.

Hundreds of prisoners have died and dozens were burned beyond recognition in a fire at a prison in Comayagua, Honduras. (Fernando Antonio/Associated Press)

"This is a problem that's existed for a long time and the solutions haven't been applied, but now we have to do something even though we don't have the money," Security Minister Pompeyo Bonilla told reporters.

The U.S. sent help from a base at Soto Cano Air Base, about 15 minutes away.

U.S. Military Staff Sgt. Bryan Franks said smoke was no longer visible above the city, and that his team included four vehicles made up of a 10-man medical team, security guards and firefighters.

Hundreds of relatives rushed to Santa Teresa Hospital in Comayagua state to learn the fate of their loved ones, Silva said.

Lucy Marder, chief of forensic medicine for the prosecutor's office, said she believed the death toll would rise and it would take at least three months to identify victims, some burned beyond recognition, because DNA tests will be required.

Honduras has 24 prisons, 23 for men or both genders, and one exclusively for women. In December, the total prison population was 11,846 of which 411 were women.