It's being called the world's deadliest prison fire in a century.
Authorities say the fire was caused by a prisoner who set his mattress ablaze in his cell in the prison in the town of Comayagua late Tuesday night.
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.
Many were trapped and died in their cells. 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.
About 475 people escaped and 356 are missing and presumed dead, said Hector Ivan Mejia, a spokesman for the Honduras Security Ministry.
Families of the inmates tried to storm the gates of the prison demanding information about their loved ones, but the crowed were driven back by officers firing tear gas.
The lockup housed people convicted of serious crimes such as homicide and armed robbery.
The Associated Press contributed to this report.