A massive fire has swept through a jail in Honduras, killing at least 300 prisoners, officials say. Many victims were burned or suffocated to death in their cells at the jail in Comayagua, in central Honduras. The officials say at least 300 are confirmed dead, but a further 56 inmates, out of the 853 in the prison, are missing and presumed dead. An inquiry is under way whether the blaze was caused by rioting or an electrical fault. Relatives of suspected victims later tried to force their way into the prison, desperate for news. Police responded by firing shots into the air and tear gas. 'Hellish' scenes The fire broke out late on Tuesday night and took more than an hour to be brought under control. Dozens of prisoners died trapped in their cells and were burned beyond recognition. Comayagua firefighters' spokesman Josue Garcia said there were "hellish" scenes at the prison and that desperate inmates had rioted in a bid to escape the flames. "We couldn't get them out because we didn't have the keys and couldn't find the guards who had them," he said. Lucy Marder, who heads the forensic services in Comayagua, said that 356 people on the prison roster were unaccounted for. . "The majority could be dead, though others could have suffered burns, escaped or survived," Ms Marder said. It was feared many inmates had fled the prison in Comayagua, about 100km (60 miles) north of the capital Tegucigalpa. Amid the confusion, relatives gathered outside the prison to try to get information. "I'm looking for my brother. We don't know what's happened to him and they won't let us in," Arlen Gomez told Honduran radio. Local hospitals are treating dozens of people for burns and other injuries. Some of the injured have been taken to Tegucigalpa for treatment, among them 30 people with severe burns. Firefighters said they had struggled to enter the prison because shots had been fired. Honduran media reported that there had been a riot in the prison before the fire broke out. Prison service head Daniel Orellana denied this. "We have two hypotheses. One is that a prisoner set fire to a mattress and the other one is that there was a short-circuit in the electrical system," he was quoted as saying by Reuters. Prisons in Honduras, which has the world's highest murder rate, are often seriously overcrowded and hold many gang members.