But as vicious attacks by Sunni militias intensified, perception of the enemy shifted, and Iraq's two main sects began fighting each other.

The Sunni militias, on the other hand, "are killing anyone who is Shiite," Aziza said.

Sunnis have even helped to protect Shiite neighbors from Sunni militias.

Sunni militias have been active in Baghdad, too.

Meanwhile, as Reuters reports, there is a bombing campaign against Sunni militias.

In the worst case, a purge could prompt some commandos to join the insurgency or evolve into a Sunni militia beyond government control.

The initial version of the events at Taji, as given by the Iraqi Interior Ministry, was a shootout between rival Sunni militias.

The Sunni militia, in its account of the incident, said the raiders were members of Al Fatah.

Iraqi police say a member of a government-allied Sunni militia along with three of his sons have been killed in a pre-dawn attack south of Baghdad.

A spokesman for a Sunni Muslim militia, the People's Liberation Army, said two of its combatants were killed in the clashes.