Prison authorities evacuated about 200 inmates from the smoke-filled parts of the building into a jail yard, the Bio Bio radio station reported. A firefighter and two prison guards also received injuries, Chile's online media reported.
Chilean President Sebastian Pinera promptly called the prison conditions unacceptable and promised reforms, adding to the challenges facing his government since he came to power earlier in 2010.
> Pinera earlier had to deal with the devastation caused by a magnitude 8.8 earthquake in February and calls for radical reforms in the country's vast mining sector after the miraculous rescue Oct. 13 of 33 miners trapped underground.
The fire started after feuding inmates from rival prison gangs set fire to mattresses during a fight in Santiago's San Miguel prison. The flames spread through the crowded building, trapping many of the inmates in the fire, La Tercera newspaper reported on its Web site.
Officials said the fire was the deadliest on record in Chile's overcrowded prison system. Calls for reform of the prisons were made earlier by campaigners and opposition critics but previous governments put aside changes, pleading lack of resources.
Officials said the fire likely started in one of the prison's five towers during the early morning fight between prisoners. Television reports showed smoke billowing out of the building and anxious relatives of inmates gathered at the entrance. There were scuffles between prison guards and angry relatives.
Luis Masferrer, the director of the national prison police, told news media the law enforcement officers had been calling for reforms in the system, in particular measures to alleviate crowding. At least 1,960 prisoners were in the building, which was designed for fewer than 1,000 inmates, when the fire broke out.
Rescuers fought the flames for about three hours before the fire could be controlled, officials said.
There were emotional scenes outside the prison as officials began informing relatives of those who died in the fire. However, families accused the prison officials of not doing enough to ensure the names of those killed or injured were announced with clarity.
Health Minister Jaime Manalich said the 14 injured were listed in critical condition because of serious burns.
Pinera said prison reforms would be expedited to prevent a repeat of Wednesday's "hugely painful tragedy" and sympathized with families of the victims.
"We cannot keep living with a prison system which is absolutely inhumane," he added.
"We are going to speed up the process to ensure our country has a humane, dignified prison system that befits a civilized country."