Baghdad, Iraq ? Car bombs killed at least 16 people and injured dozens Sunday in Baghdad and a Shiite holy city, casting doubt on U.S. hopes that formation of a new government alone would provide a quick end to the country’s violence.

At least 26 others were killed or found dead Sunday, including a U.S. Marine mortally wounded in the insurgent bastion of Anbar province in western Iraq, police and the U.S. military said.

Some of the victims appeared to have been abducted and killed by sectarian “death squads” that target members of rival religious communities. The dead included three brothers whose charred bodies were found before dawn in Baghdad’s Dora district, a mixed Sunni-Shiite area and one of the city’s most violent.

The deadliest single attack occurred at midmorning when a suicide driver detonated his vehicle near an Iraqi army patrol leaving its base in the Sunni Arab neighborhood of Azamiyah, killing 10 people and injuring 15, most of them Iraqi soldiers, police Lt. Col. Falah al-Mohammedawi said.

A half-hour earlier, a car bomb exploded near the Baghdad offices of the state-run al-Sabah newspaper, killing an employee, police Lt. Ahmed Mohammed Ali said. Officials believed the target was a police patrol that passed by shortly before the blast.

A woman reacts following a car bomb attack in the Shiite holy city of Karbala, 60 miles south of Baghdad. Two car bombs rocked northern Baghdad neighborhoods Sunday morning within a span of half an hour, while another struck Karbala. The car bombs left at least 16 dead and 49 wounded.

In Karbala, a Shiite holy city 60 miles south of Baghdad, a suicide car bomber exploded his vehicle near the main provincial government building, killing five people and wounding 19, police spokesman Rahman Mishawi said.

The bomber was unable to reach the government building because of concrete barricades and a police cordon and instead set off his explosives about 300 yards away, police said.

Sectarian violence has forced about 14,700 Iraqi families – or about 88,000 people – to flee their homes, a senior Iraqi official said Sunday. The official, Suhaila Abed Jaafar, doubted they could return without “concerted military action” to restore order in their communities.

In London, the British Defense Ministry said “up to five” British personnel had been killed in Saturday’s helicopter crash in Basra. British officials have not confirmed Iraqi police and witness reports that the Lynx helicopter was shot down.

Basra, Iraq’s second-largest city, was calm Sunday after a day of violence when about 250 Iraqis cheered wildly, hurled stones and fired gunshots at British troops who had rushed to the crash scene. Five Iraqis, including a child, were killed in the melee, and several British troops were slightly injured.

In a bid to ease tension, Basra Gov. Mohammed al-Waeli agreed Sunday to resume cooperation with British authorities, which he broke off four months ago after British troops cracked down on policemen with links to Shiite militias.

Britain’s new defense secretary, Des Browne, told Sky News that the unrest in Basra does not mean the security situation has deteriorated there, saying the number of rioters was small in a city of about 1.5 million.