The gunmen roamed Sunni neighborhoods in Tal Afar through the night, shooting at residents and homes.
BAGHDAD -- Shiite militants and police enraged by deadly truck bombings went on a shooting rampage against Sunnis in a northwestern Iraqi city Wednesday, killing as many as 70 men execution-style and prompting fears that sectarian violence was spreading outside the capital.
The killings occurred in the mixed Shiite-Sunni city Tal Afar, which had been an insurgent stronghold until an offensive by U.S. and Iraqi troops in September 2005, when militants fled into the countryside without a fight. Last March, President Bush cited the operation as an example that gave him "confidence in our strategy."
The gunmen roamed Sunni neighborhoods in Tal Afar through the night, shooting at residents and homes, according to police and a local Sunni politician. Witnesses said relatives of the Shiite victims in the truck bombings broke into Sunni homes and killed the men inside or dragged them out and shot them in the streets.
Gen. Khourshid al-Douski, the Iraqi army commander in charge of the area, said 70 were shot in the back of the head and 40 people were kidnapped. A senior hospital official in Tal Afar, who spoke on condition of anonymity out of security concerns, said 45 men were killed.
Outraged Sunni groups blamed Shiite-led security forces for the killings. Prime Minister Nouri al-Maliki's office ordered an investigation and the U.S. command offered to provide assistance.
Ali al-Talafari, a Sunni member of the local Turkomen Front Party, said the Iraqi army had arrested 18 policemen accused in the shooting rampage after they were identified by Sunni families. Shiite militiamen also took part, he said.
The revenge killings among Shiites in the religiously mixed city 260 miles northwest of Baghdad were triggered by truck bombings in Tal Afar on Tuesday that killed 80 people and wounded 185.
Al-Douski said one of the trucks exploded after the driver lured people in a predominantly Shiite neighborhood to the site by telling them he was distributing free flour from a humanitarian organization. The bombing caused surrounding buildings to collapse, leaving huge piles of concrete and bricks dusted with white flour.
Videotaped footage from the scene was broadcast Wednesday night showing a man dead in the front seat of his car. Men and women carried the limp bodies of children powdered with flour. Others dug through the rubble with their bare hands in a search for survivors.
The hard-line Sunni Association of Muslim Scholars said the revenge killings were evidence "of the clear plot and coordination between the militias and the government forces of interior and defense." The Iraqi Accordance Front, the biggest Sunni parliamentary group, said the killings proved the need for an overhaul of Iraq's Shiite-dominated system.
"If yesterday's attacks were carried out by unidentified terrorists, today's events were conducted by well-known criminal policemen and they must be punished," Sunni lawmaker Dhafer al-Ani said. "The whole situation in Iraq needs to be reconsidered and a quick solution is needed to the political process."
Tal Afar, about 90 miles east of the Syrian border, is mainly populated by ethnic Turks, with Shiites making up about 60 percent of the 200,000 residents.
The city, which is known for tomatoes and cattle, has suffered frequent insurgent attacks, despite sand barriers erected around it by U.S. and Iraqi forces. But the situation had been calm in recent months and some displaced Shiite and Sunni families had started to return to their homes.
Army troops moved into Sunni areas of the city Wednesday to stop the violence, confining police to their bases and enacting a curfew. Calm was restored by mid-afternoon, said Wathiq al-Hamdani, the provincial police chief, and his head of operations, Brig. Abdul-Karim al-Jibouri.
Hundreds of residents -- including relatives of bombing victims -- rallied later Wednesday, demanding the resignations of the police chief and the mayor, as well as the release of the detained Shiite policemen.
Meanwhile, U.S. officials remained cautiously optimistic about a security crackdown that is entering its seventh week in Baghdad. The U.S. has sent about 30,000 extra troops to assist in the operation, which many see as a last-ditch attempt to bring peace to Iraq.
"We are seeing preliminary signs of progress," U.S. military spokesman Rear Adm. Mark Fox said Wednesday, but he cautioned that "there will be rough days ahead."
"Progress does not come without a cost," he said. "Like backing a rat into a corner, increasing pressure on the extremists by limiting their available resources and places to hide leads to desperate changes in tactics."
The new tactics included using chlorine, a highly toxic chemical, in at least eight bombings since Jan. 28. On Wednesday, suicide bombers detonated explosives on trucks carrying the chemical outside the Fallujah government center, about 40 miles west of Baghdad.
About 15 U.S. and Iraqi security forces were wounded in the attack, although the bombers were shot and set off their explosives before reaching government buildings, the U.S. military said.
At least 44 people were killed or found dead elsewhere in Iraq, including four people in two car bombings in Baghdad. A parked car bomb struck a market in the predominantly Shiite city of Mahaweel, south of Baghdad, killing at least four people.