A fire in a prison in the Chilean capital Santiago has left at least 81 inmates dead, officials say.
The blaze broke out in the San Miguel prison at 0530 local time (0830 GMT), with television pictures showing smoke billowing from the building.
Hundreds of inmates were evacuated, with up to 14 prisoners said to have life-threatening injuries.
President Sebastian Pinera described the prison system as "inhumane" and said reforms should be speeded up.
He said the fire was a "hugely painful tragedy".
"We cannot guarantee the number of dead will not rise," he said.
The president at one point said 83 had died, but officials later revised this figure down.
Reports said the fire broke out after a fight between rival gangs, who set mattresses on fire.
Health Minister Jaime Manalich said this was the deadliest incident in the history of the Chilean prison service.
The BBC's Gideon Long in Santiago says the fire is now under control but there are chaotic scenes as relatives wait at the prison, with police trying to control the situation.
There are up to 5,000 people outside the prison, and many relatives still do not know the fate of their loved ones.
"We have been here for hours, and they haven't told us anything," one woman said.
There was confusion earlier when officials read out partial lists of survivors, Reuters news agency said.
Some relatives reportedly screamed, assuming that inmates not mentioned on the list were dead.
But no definitive list of the dead has yet been produced, as some bodies are charred beyond recognition.
The evacuated inmates are being held in a sports ground within the prison.
Our correspondent says local media are reporting that 1,900 inmates were in the jail, although it has a capacity for only about 700.
The situation prompted President Pinera to call for an end to overcrowding.
"We cannot keep living with a prison system which is absolutely inhumane," he said.
"We are going to speed up the process to ensure our country has a humane, dignified prison system that befits a civilised country."
There were reports that prison guards had initially prevented firefighters from entering the prison, which is in the south of the capital, La Tercera newspaper said.
The television pictures showed some prisoners waving their hands through the bars of the jail as relatives screamed at security forces to allow them in to help.
An investigation is under way into the cause of the blaze.
Chile has one of the highest per capita number of prisoners in Latin America.