Baghdad, Iraq ? Gunmen sprayed grenades and automatic weapons fire in a market south of Baghdad on Monday, killing at least 50 people, mostly Shiites. The sectarian attack drew an angry protest from lawmakers who accused Iraqi forces of standing idly by during the rampage.

Women and children were among the dead and wounded in the assault in Mahmoudiya, long a flashpoint of Shiite-Sunni tension, hospital officials said. Late Monday, police said they found 12 bodies in different parts of town – possible victims of reprisal killings.

Several witnesses, including municipal council members, said the attack began when gunmen – presumed to be Sunnis – fired on the funeral of a member of the Mahdi Army, a Shiite militia, killing nine mourners.

Assailants then drove to the nearby market area in the town 20 miles south of Baghdad, killing three soldiers at a checkpoint and firing rocket-propelled grenades and automatic rifles at the crowd. After the gunmen sped away, they lobbed several mortar rounds into the neighborhood, the witnesses said.

The assault occurred a few hundred yards from Iraqi army and police positions, but the troops did not intervene until the attackers were fleeing, the witnesses said. They spoke on condition of anonymity because of fear of reprisals.

Security shortcomings

A destroyed market remains empty after being raided by armed gunmen early Monday in Mahmoudiya, just south of Baghdad, Iraq. Dozens of heavily armed attackers raided the open air market, killing at least 50 people, Iraqi and U.S. officials said. Most of the victims were believed to be Shiite Muslims.

In Baghdad, Shiite legislator Jalaluddin al-Saghir said Iraqi military authorities had ignored warnings that weapons were being stocked in a mosque near the market. He also said the local police commander refused to order his men to confront the attackers because they lacked weapons and ammunition.

Dozens of Shiite lawmakers, including followers of radical anti-American cleric Muqtada al-Sadr, stormed out of a parliament session to protest the performance of the security forces.

In the first 17 days of July, at least 617 Iraqis have been killed in war-related violence, at least 527 civilians and 90 police and security forces, according to an AP count. In the nearly two months since the unity government took office on May 20, more than 1,850 Iraqis have been killed, including at least 1,585 civilians and 267 security forces. The figures do not include insurgents.

The 617 killed so far this July is already near the total killed in all July last year: 714.

Tit-for-tat attacks

The Shiite television station Al-Forat broadcast strident quotes from Shiites who blamed the attack on Sunni religious extremists. They expressed outrage that Sunni politicians could not rein in the militants.

The main Sunni bloc in parliament said the attack may have been retaliation for the kidnapping of seven Sunnis whose bodies were found Sunday in Mahmoudiya. The bloc accused Shiite-dominated Iraqi security forces of failing to control the situation.

The events also raised doubts about the effectiveness of the U.S. strategy of handing over large areas of the country to Iraqi control, while keeping U.S. troops in reserve.

U.S. troops of the 101st Airborne Division reported hearing detonations and gunfire, the U.S. command said. But Iraqi troops are responsible for security in Mahmoudiya, and American soldiers do not intervene unless asked by the Iraqis.

Four soldiers and a former soldier from the division are accused of raping and murdering a teenage girl near Mahmoudiya on March 12. A sixth soldier is accused of failing to report the crime.

The Mahmoudiya attack was part of a rising tide of tit-for-tat killings and intimidation that many Iraqis fear is the prelude to civil war. The campaign of intimidation and attacks is slowly transforming Baghdad into sectarian zones under the tacit control of armed groups that protect members of their sect and drive away others.