MEXICO CITY — A fire that broke out apparently when an inmate set a mattress ablaze in an overcrowded Honduran prison left as many as 350 inmates dead Wednesday as investigators pulled one body after another from the smoldering facility.

The fire, which started at 10:50 p.m. Tuesday at the Comayagua National Penitentiary, took firefighters three hours to put out.

Guards fired their guns repeatedly to keep screaming trapped inmates from escaping.

"It is a day of deep pain for Honduras," President Porfirio Lobo said in a brief televised address, acknowledging that a criminal hand may have been behind the disaster.

"We will conduct an investigation to determine what provoked this lamentable and unacceptable tragedy and find those responsible," Lobo said.

The death toll climbed throughout the day. At noon, Security Minister Pompeyo Bonilla said he thought that "more than 300" were dead. National Prison Director Danilo Orellana later told Honduran media that the toll had surpassed 350. At least one woman who was in the prison illegally was said to be among the fatalities.

Hundreds of other prisoners were burned in the blaze or injured when they broke through a roof and jumped to safety, hospital officials said.

Anguished relatives banged on the gates and threw rocks at riot police and soldiers who were blocking access to the prison in Comayagua, a city about 55 miles north of Tegucigalpa, the country's capital. Police responded with tear gas. Gunfire also rang out.

Riot police also closed off all public access to the morgue in Tegucigalpa where bodies were taken as relatives clamored for information about the identities of the victims.

Orellana, the prisons director, said early indications were that "an inmate may have caused the fire by setting his mattress alight. Some of his cellmates said that he shouted, 'We will all die here,' and within five minutes everything was burning."

Photos showed metal cell bars that had twisted and melted from the heat.

Security agents outside the one-story prison wore surgical masks as the stench of burned flesh lingered. White body bags piled up outside the yellow entrance to the building.

"When the fire started, we shouted at (the guards) with keys but they wouldn't open for us. In fact, they fired at us," inmate Ruben Garcia told Honduras' El Heraldo newspaper.

As the raging fire consumed more of the prison, guards ushered survivors out of the jail. Many emerged shirtless, bearing burn marks on their tattooed torsos.

Injured prisoners were taken to hospitals in Comayagua and Tegucigalpa.

Chile sent a team of forensic specialists to help identify the victims, but authorities said the process could take days.

"The majority of the victims are unrecognizable," said Daniela Ferrera of the State Attorney General's Office.