BAGHDAD (AP) – Dozens of Shiite villagers in the north were massacred by Sunni extremists, two officials said Tuesday, while a car bomb exploded across the street from the Iranian Embassy in the heart of Baghdad and killed four civilians.

Also Tuesday, Shiite legislators loyal to anti-U.S. cleric Muqtada al-Sadr decided to end their five-week boycott of parliament, one of their leaders said. The Shiite protest along with a separate Sunni boycott had blocked work on key benchmark legislation demanded by the U.S. Police Col. Ragheb Radhi al-Omairi said 29 members of a Shiite tribe were massacred overnight in Diyala province when dozens of suspected Sunni gunmen raided their village near Muqdadiyah, about 95 kilometers (60 miles) northeast of Baghdad. The dead included four women, al-Omairi said. Al-Omairi said he had not seen the bodies and it was unclear whether they had been retrieved.

An Iraqi army officer, who spoke on condition of anonymity because he was not supposed to release the information, said the attack occurred in the village of Diwailiya and that at least 10 bodies were mutilated in the hour-long raid.

In Baghdad, the blast near the Iranian Embassy occurred in late morning a few hundred yards north of the U.S.-controlled Green Zone, sending a huge cloud of black smoke over the city. Three civilians also were wounded, said police who spoke on condition of anonymity because they were not authorized to release information.

Also Tuesday, the bodies of two security guards were found in the western Baghdad neighborhood of Mansour, two days after they were kidnapped from the office of a cell phone company where they worked, police said.

American forces have launched offensives around the Iraqi capital to try to halt the flow of bombs and fighters into the city. The latest strike began Monday southwest of the city in an area where al-Qaeda and other groups have been active for years.

On Tuesday, the U.S. command announced that American soldiers had killed about a dozen insurgents during a three-hour gunfight the day before in the Fadhil district, a Sunni enclave in the center of the city. The battle began when paratroopers from the 82nd Airborne Division came under fire from the Islamic Bank building, the military said.

One U.S. trooper was slightly wounded, the U.S. said. The leader of the 30-member Sadrist bloc in parliament, Nasser al-Rubaie, said the decision to end the boycott was taken after the government agreed to rebuild a Shiite mosque in Samarra which was destroyed in two bombings and to secure the highway from Baghdad and the shrine.

Pressure is now expected to mount on the Sunnis to end their boycott, which began over the ouster of the Sunni speaker of parliament last month. Sunni leaders say agreement is near on ending the protest.

Both protests have paralyzed work in Iraq’s fractious, 275-member assembly as pressure is growing in the United States to bring an end to the U.S. military role here.

To the south, commercial air service resumed Tuesday at Basra’s international airport after rocket or mortar fire damaged the runway, a British spokesman said.

The attack in Basra occurred Monday, causing minor damage and a one-day suspension of commercial air service, British spokesman Maj. Matthew Bird said. There were no casualties, he said.

Basra’s airport is controlled by British troops who come under almost daily attacks from Shiite militiamen in the southern oil-producing region. Al-Sadr’s Mahdi Army militia and other Shiite factions are competing for control of the area.

In Kirkuk, families collected the bodies of relatives from hospitals a day after a triple bombing killed about 80 people. Others were searching debris still left on the street, hoping for clues about what happened to friends and relatives whose bodies have not been identified.

All but one of the victims died when a massive truck bomb exploded near the Kirkuk Castle and the headquarters of the Patriotic Union of Kurdistan, the party of Iraqi President Jalal Talabani.

It was the deadliest attack in Kirkuk, 290 kilometers (180 miles)north of Baghdad, where Arabs, Turkomen and Kurds are competing for control of the city at the heart of Iraq’s northern oil region.

Saman Ahmed, 35, said he was driving along the street when the blast “pushed other vehicles toward my car along with fire and shrapnel like a flood.” “The glass from my car and the other cars went into my face,” he said from his hospital bed. “Now I cannot hear well because of the sound of the explosion. I saw tens of dead bodies lying on the ground.” Voters in the city are to decide whether to join the Kurdish self-ruled region in a referendum by year’s end.

With three ethnic groups competing for control, violence in Kirkuk has been frequent. But Monday’s blasts were on a far bigger scale than most attacks.

U.S. and Iraqi officials have said Sunni Arab insurgents are moving farther north to carry out attacks, fleeing U.S. offensives in and around Baghdad.

Maj. Gen. Jamal Tahir, the Kirkuk police chief, said he believed that U.S.-led military operations around Baqouba pushed al-Qaeda in Iraq’s elements to flee to the nearest cities. “Some of them came to Kirkuk because they have loyalists here and they started to carry out terrorist acts,” he told The Associated Press.

Monday’s explosions occurred just over a week after one of the Iraq conflict’s deadliest suicide attacks hit a Turkomen Shiite village about 80 kilometers (50 miles) south of Kirkuk, killing more than 160 people.