"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.
National prison police director Luis Masferrer said the blaze broke out about 5:30 a.m. (7:30 a.m. EST; 1230 GMT) 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.
Pinera told reporters the number of dead had risen to 83, but Santiago region Gov. Fernando Echeverria said later that the official number of dead was still 81.
