Seven prisoners died of smoke inhalation after rebelling inmates set fire to mattresses in a prison near Sao Paulo, authorities said Thursday.

The bodies of the prisoners were removed from the lockup in the city of Jundai early Thursday after officials regained control of part of the prison, said Carlos Gati, a spokesman for the Sao Paulo state public safety department. Jundai is about 19 miles west of Sao Paulo.

The rebellion started Wednesday after prisoners protested the transfer of some inmates to another facility. Prisoners still controlled another part of the facility Thursday morning and were holding three prison workers hostage, Gati said. The prison has a capacity of 120 inmates, but 470 are being held there.

Authorities were negotiating with the prisoners in an attempt to end the standoff, Gati said. There was extensive damage to the prison, but officials did not know what conditions were like in the part of the facility still being held by inmates or whether there might be additional fatalities or inmates suffering from injuries, he said.

"The situation is still very confusing there," he said.

Prison rebellions occur on an almost weekly basis in Brazil, where inmate overcrowding is common and human rights advocates describe prison conditions as inhumane. On Tuesday, inmates released 10 hostages at a detention center in Mogi das Cruzes, a small city about 30 miles east of Sao Paulo.

A January prison uprising in Brazil's remote Amazon jungle state of Rondonia left four dead. That prison was also the site of a bloody five-day uprising in April 2004 that left 14 inmates dead, many of them hacked to death and tossed from the prison's roof.

Also in 2004, 30 prisoners and one officer died during a three-day rebellion at the Benfica detention center in Rio de Janeiro.