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

"The conditions that existed inside this prison are absolutely inhumane," said Chilean President Sebastian Pinera, who visited an emergency center where inmates were being treated for severe burns and smoke inhalation.

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

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

Firefighters said they were alerted to the fire by the cell-phone call inside the prison.

The fire department said firefighters arrived nine minutes after the initial alarm at 5:48 and found a violent blaze spread over a large part of the fourth floor of Tower 5. Firefighters cut through several locks, allowing them to save 60 inmates, it said.

Firefighters had to work with police to avoid problems with the rioting prisoners.

Health Minister Jaime Manalich called it an "enormous calamity," and it appeared to be the worst disaster in the history of Chile's prisons. A fire in a northern prison killed 26 people in 2001.

Hundreds of worried and angry relatives of inmates gathered in a chaotic scene outside the gates of the prison, a collection of concrete towers that rise above a middle-class neighborhood. Some waited six hours before officials read out the names of survivors - which people mistook for those of the dead. Some spat or hurled rocks at Masferrer, the head of the nation's prison police.

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

Pedro Hernandez of Chile's prison guards' union said there were only five guards to watch over the prisoners. The president said there were six guards in the towers where inmates are held, and 26 others were stationed at the perimeter.