State TV news reported that a brawl broke out at Ghezel Hesar prison in the city of Karaj, just to the west of Tehran, during a recreation period and was broken up by security forces after nine hours.

The semi-official Mehr news agency said the deaths were the result of clashes that ensued after an escape attempt by convicted smugglers who face the death penalty.

“Due to the powerful presence of officials and cooperation of some other prisoners who were against their actions, their effort to escape was in vain,” Mehr quoted a prison official as saying.

The escape attempt involved sabotage and arson and prison guards were attacked, Mehr said, but it did not give details of any injuries among staff.