Gunmen roaming a Baghdad neighborhood on Sunday killed at least 40 unarmed Iraqis as soon as they identified them as Sunnis, emergency police said.
Ala'a Makki, a spokesman for the Iraqi Islamic Party -- Iraq's main Sunni political movement -- said the victims included women and children.
He called the killings in Hay al Jihad "one of the biggest massacres of Sunnis."
Gunmen -- mostly "young reckless teenagers" -- started to pick up Sunni youth and execute them in public, while others went door-to-door looking for Sunni families who stayed behind, Makki said.
After warning one Iraqi woman she had 10 seconds to leave, the gunmen killed her and her children, Makki said.
A member of the Iraqi Islamic Party was dragged out of his house at 7 a.m. and executed, he said.
A witness in the Hay al Jihad neighborhood said he walked outside his home and saw the main street lined with bodies, and the attackers setting fire to homes.
He said residents tried to call the Ministries of Interior and Defense, without success.
Makki blamed the Mehdi militia loyal to radical Shiite cleric Muqtada al-Sadr.
The violence continued for eight hours, Makki said, blaming the Ministries of Interior and Defense for not responding, and saying U.S. forces responded too late to stop most of the killings.
The violence in the Baghdad neighborhood follows an insurgent car bomb attack on a Shiite place of prayer in the same neighborhood Saturday night. Police said that assault killed two people and wounded 13 civilians.
On Friday, a car bomb detonated outside a Sunni mosque in the same neighborhood, although the casualty count was not clear.
Makki said after the Shiite mosque was attacked Saturday night, the Mehdi militia warned Sunni residents to leave the neighborhood immediately or face death.