SANTIAGO, Chile - A fire that began during a riot in a severely overcrowded prison killed at least 81 inmates yesterday and seriously injured 14 others, officials said. Chileans nationwide could hear the screams of inmates after a prisoner using an illegal cell phone called state television for help.

National prison-police director Luis Masferrer said the blaze broke out about 5:30 a.m. (7:30 a.m. EST) at the San Miguel prison south of the capital, and it was brought under control three hours later.

Preliminary reports indicated the fire was set intentionally, said investigator Alejandro Pena. Interior Minister Rodrigo Hinzpeter said it started during fighting between inmates and reached its maximum intensity in just three minutes.

Prison officials said the first call to firefighters came about 20 minutes after the fight began.

Hundreds of anxious and angry relatives of inmates gathered in a chaotic scene outside the prison gates. Some spat or hurled rocks at Masferrer.

Police-operations director Jaime Concha insisted that police acted quickly despite coping with 1,900 inmates at the prison built for 700.

In October, Judge Ana Maria Arratia Valdebenito warned that Tower 5, where the fire began, held 484 prisoners - more than 100 per floor. Many died there.

Pedro Hernandez, who directs Chile's prison-guards union, said there were only five guards to watch over the prisoners.

Chile's firefighters said in an official statement that they were alerted to the fire by a call from a cell phone inside the prison, a collection of cement towers that rises above a middle-class neighborhood.

An unidentified prisoner, in a call that was played on state TV, said guards "laughed and took photos with the cell phones of the inmates who were vomiting [from smoke] . . . and didn't do anything."