BAGHDAD, Iraq — Dozens of policemen were missing today and at least six were dead after insurgents ambushed a police convoy near a U.S. base, officials said. A series of bombings killed at least five people in three Iraqi cities.

Insurgents set off roadside bombs and then opened fire Thursday night on a large police convoy near the U.S. base of Taji, just north of Baghdad. The policemen from the Shiite shrine city of Najaf, south of Baghdad, were returning home after picking up new vehicles at the base, police said.

A senior official in the Najaf governor's office said only 35 of the 80 policemen had returned by today to the city.

The attackers shouted "God is great!" and "Long live jihad!" as they swarmed about the burning vehicles firing at the police, survivors told authorities. Most of the vehicles were destroyed.

A senior official in the Najaf governor's office said only 35 of the 80 members of the convoy had made it back to the city. The others were either dead or unaccounted for, he said.

In other attacks, a pair of roadside bombings near two Sunni mosques in the city of Baqouba killed least four civilians and wounded six, police said. The two mosques — Saad bin Maath mosque in the city's New Baqouba district and the al-Aqsa mosque in Katoun — are about a mile apart, officials said.

A suicide car bomber in the southern province of Basra targeted a British military convoy outside the Shuaiba military base about 13 miles southwest of Basra city, killing at least one civilian and wounding four British troops, police said.

In the northern city of Mosul, at least seven people were wounded in another suicide car bomb attack on a police station, police said. Police saw the vehicle coming and fired at the driver, preventing him from entering the compound, an official said.

Back in Baghdad, police discovered the body of a handcuffed man, shot in the head, in the southern neighborhood of Dora.

On the political front, leaders of the Shiite political alliance said today that they will attend next week's parliament session even if they haven't reached agreement on names for the top political posts in Iraq's next government.

Members of the alliance will meet this weekend to discuss the posts — including the position of prime minister, at the core of the political debate behind a long-standing stalemate — and also attend the parliament session, scheduled for Monday, said Sabah al-Saedi, a Shiite politician.