Police removed bodies from the scene of the jailbreak in a pick-up truck
Six Iraqi policemen and seven detained militants have been killed in the city of Ramadi as the prisoners attempted to escape from a police station.
The shoot-out happened in the early hours of the morning in the city, some 100km (60 miles) west of Baghdad.
One of the militants overpowered an officer as he was being escorted from his cell in what appeared to be a well-planned operation, police said.
The militants were reported to be senior figures with links to al-Qaeda.
The jailbreak occurred about 0200 (2300 GMT)
Three of the detained group of men managed to escape during the gun battle. Six police officers were wounded by gunfire.
Ramadi police have imposed a curfew across the city following the incident. Police are searching through houses in the city for the escaped militants.
A source quoted by AFP news agency said the first inmate to attempt to break free seized the police officer's weapon during a toilet break and shot him.
"He then opened up the other cells and he and his fellow prisoners grabbed weapons from the police station's armoury, opening fire on the policemen," the source said.
The mainly Sunni Arab city, capital of Anbar province, was a major al-Qaeda stronghold after Saddam Hussein was ousted by US-led forces in 2003.
But there has been less violence since local Sunni Arabs began supporting US efforts against al-Qaeda in late 2006.