Separate drive-by shootings by suspected insurgents Wednesday in Iraq killed 11 civilians on their way to work in a company bus and the director of public relations for Iraq's Defense Ministry, police said.

An Iraqi soldier inspects the blindfolds on some of 16 suspected insurgents who are detained by Iraqi military near Baqouba, 60 kilometers (35 miles) northeast of Baghdad, Tuesday, May 9, 2006. Large quantities of ammunition, improvised explosive devices (IEDs) and mortar shells were recovered in a joint US-Iraqi Army operation in Baqouba on Tuesday, police said. [AP]

The violence followed a suicide truck bomb attack in a crowded market in Tal Afar late Tuesday, which killed at least 20 people and wounded more than 130 in a city cited by President Bush as a success story in battling insurgents.

Meanwhile, leaders of Sunni-Arab, Shiite and Kurdish tribes were holding a conference in Baghdad to discuss ways of promoting unity in Iraq and reducing sectarian violence. Ashraf Qazi, the U.N.'s special envoy in Iraq, was one of the attendees.

Legislators also met in Baghdad's heavily fortified Green Zone to discuss procedural issues such as the formation of parliamentary committees.

Incoming Prime Minister Nouri al-Maliki said Tuesday that he had almost finished assembling a Cabinet, the final step in establishing a national unity government. U.S. officials had predicted insurgents would step up attacks to try to block the new administration.

U.S. Ambassador Zalmay Khalilzad said al-Maliki would soon launch a four-part plan to restore order by securing Baghdad, Basra and eight other cities, promoting reconciliation, building public confidence in the police, and army and disbanding sectarian militias.

Wednesday's worst attack occurred about 9 a.m. near Baqouba, 35 miles northeast of Baghdad, when suspected insurgents riding in a car opened fire on a bus, killing at least 11 Iraqi passengers and wounding three, police said.

The victims were heading to work at a state-run electronics company that makes products such as television sets, and the bus was operated by their company.

In Baghdad, suspected insurgents fatally shot Mohammed Musaab Talal al-Amari, a Shiite who directs the Defense Ministry's public relations office, said police Capt. Jamil Hussein.

Al-Amari was on his way to work when his car was stopped by another vehicle in the residential neighborhood of Bayaa, Hussein said. Three men then got out of another car and opened fire, killing al-Amari and wounding an Iraqi pedestrian, he said.

The suicide attack in Tal Afar, 260 miles northwest of Baghdad, occurred Tuesday evening as shoppers were scurrying to finish their purchases before closing, police said. The attacker had attracted a crowd of people to his pickup truck by hawking flour at half-price, police said.

Lt. Col. Ali Rasheed of the Interior Ministry said the main target of the bombing may have been a police station within the market area.

The director of the city hospital, Saleh Qado, said 20 people were killed and 70 wounded, but the U.S. command said Wednesday that 134 Iraqis were wounded, at least 24 of them critically.

As casualties mounted at the local hospital, the overflow of wounded were taken to nearby coalition medical facilities, the command said. Some of the critically wounded also were flown on coalition aircraft to hospitals in Mosul and Tikrit.

At least 500 Iraqis have been killed by vehicle bombs in 2006, out of a total of at least 3,525 Iraqis killed in war-related violence this year. These numbers include civilians, government officials, and police and security officials, and are considered only a minimum based on Associated Press reporting.

In March, President Bush praised American efforts to stabilize Tal Afar, saying he had "confidence in our strategy" and that success in the city "gives reason for hope for a free Iraq."

U.S. and Iraqi forces launched an operation in September to clear the city of insurgents ¡ª the second such attempt in a year. However, by the end of that month a woman suicide bomber slipped into a crowd of recruits, killing at least six people and wounding 30. Since then, the city has been hit by repeated suicide attacks.

Tal Afar's population is a volatile mix of Turkomen, Kurds and Arabs, which complicates efforts to control the city. Trouble started in 2003 when Kurdish fighters took over the city, angering the majority Turkomen population.

Insurgents are also believed to have used Tal Afar as a hub for smuggling weapons and fighters from Syria, about 90 miles to the west.