Five separate shootings killed at least 15 Iraqis yesterday, including 11 civilians who were traveling to work in a company bus and the director of public relations at Iraq's defense ministry, police said.
Casualty figures from a suicide truck bomb attack in the northern city of Tal Afar on Tuesday night also rose to 22 dead and 134 wounded, officials said. The US military flew some of the wounded to other cities when the local hospital was overwhelmed.
Meanwhile, efforts continued to reduce sectarian violence in Iraq.
Leaders of Sunni Arab, Shiite and Kurdish tribes met in Baghdad to discuss ways of promoting unity in Iraq. UN envoy Ashraf Qazi was invited but was out of the country.
Legislators also met in Baghdad's heavily fortified Green Zone to discuss procedural issues such as the formation of parliamentary committees.
Iraqi prime minister-designate Nouri al-Maliki said on Tuesday that he had almost finished assembling a Cabinet, the final step in establishing a national unity government. US officials had predicted insurgents would step up attacks to try to block the new administration.
US 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.
Yesterday's worst attack occurred about 9am near Baqubah, 60km 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 on condition of anonymity out of concern for their own safety.
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, police said.
In Baghdad, suspected insurgents riding in two BMWs assassinated a defense ministry official as he drove to work at about 8:15am, police said.
One of the BMWs stopped to block the private car of Mohammed Musab Talal al-Amari, a Shiite who directs the ministry's public relations office, said police Captain Jamil Hussein. Three men then got out of the other BMW and opened fire in the residential neighborhood of Bayaa, killing al-Amari and wounding an Iraqi pedestrian, Hussein said.
The defense ministry controls Iraq's military.
In two other shootings in Baghdad, suspected insurgents killed a Shiite taxi driver and a Shiite who once belonged to Iraq's disbanded Baath party, police said. A similar attack killed a civilian driver about 130km south of the capital, police said.
Police also said that an ambush by insurgents killed four off-duty policemen in Ramadi on Tuesday, apparently as they were leaving work. Ramadi, 115km west of Baghdad, is located in Anbar Province, where many Sunni-led insurgent groups are based.
The suicide attack in Tal Afar, 420km northwest of Baghdad, occurred at 8:30pm on Tuesday as shoppers were scurrying to finish their purchases before closing, police said.
Lieutenant Colonel Ali Rasheed of the interior ministry said the main target of the bombing may have been a police station within the market area.
"We were manning a checkpoint when a truck full of flour sacks passed us and ignored our orders to stop, so I shot at the truck and seconds later it exploded, throwing me to the ground," policeman Arakan Youssif said in an interview yesterday.