At least 11 inmates and four police officers have died in a mutiny at a counter-terrorism prison in Baghdad.
Al-Qaeda leader Huthaifa al-Batawi, accused of masterminding the deadly siege of a Baghdad church last October, reportedly led the revolt.
He grabbed an officer's gun while being led to an interrogation and shot four policemen dead, including the head of the unit.
Five other officers were wounded in crossfire before Batawi was killed.
An interior ministry official told AFP news agency that Batawi was being taken to be interrogated about possible al-Qaeda plots in Iraq to avenge the death of Osama Bin Laden when he seized an officer's gun.
He managed to free a group of other inmates before they attempted to break out of the prison in the Iraqi capital's central Karrada district in the early hours of Sunday morning, said the official.
But the would-be escapees were killed by security reinforcements.
Brigadier General Moayed al-Saleh, head of counter-terrorism in Karrada district, was killed along with a lieutenant colonel and two first lieutenants, officials said.
Batawi was among 12 people arrested last November in connection with the siege of a Catholic Church in Karrada district on 31 October.
More than 100 people were attending mass at the time, and were taken hostage. At least half of them were killed when Iraqi security forces moved in to try to free them.