Four inmates die in US prison brawl

Four inmates being held in a prison in Oklahoma have died in a brawl, the media reported.

Three prisoners died in a town near Oklahoma city while another five were injured and transported to a hospital where one of them died on Sunday, Efe news agency reported.

At least three of the dead had knife wounds, a spokesman for the penitentiary said.

The Oklahoma state prisons department, which oversees the prison, and the firm contracted to run it are investigating the incident.

The incident comes after 200 to 300 of the prison's 1,600 inmates were involved in a brawl in June.