The US military said 14 American soldiers were killed over the past three days, including four in a single roadside bombing and another who was struck by a suicide bomber while on a foot patrol. The blast that killed the four US soldiers occurred Sunday as the troops were conducting a cordon and search operation northwest of Baghdad, according to a statement. Two other soldiers were killed and five were wounded along with an Iraqi interpreter in two separate roadside bombings Sunday, the military said. In the boldest attack, a US soldier was killed Friday after the patrol approached two suspicious men for questioning near a mosque southwest of Baghdad, and one of the suspects blew himself up. Military spokesman Maj. Webster Wright said US troops also fired at the second suspect after he began acting aggressively, and the gunfire detonated his suicide vest. "Our initial analysis is that these guys were al-Qaida and were planning to launch attacks into Baghdad," Wright said in an e-mailed statement. Seven other soldiers were killed in a series of attacks across Iraq on Saturday. Combined with the previously announced death of a US soldier in central Baghdad on Friday, it was a deadly start for June. May was the third bloodiest month since the war began in March 2003, with 127 troop deaths reported. A car bomb also exploded outside a US base near the volatile city of Baqouba, leaving a number of troops gasping for air and suffering from eye irritations, the military said. It did not confirm a report in the Los Angeles Times that the car was carrying chlorine canisters and said the soldiers who were sickened had been treated and returned to duty. The attacks came days after the Pentagon announced the completion of the troop buildup ordered by President George W. Bush in January, raising the total number of troops in Iraq to about 150,000. That number may still climb as more support troops move in. The Bush administration has warned that the buildup will result in more US casualties as more American soldiers come into contact with enemy forces and concentrate on the streets of Baghdad and remote outposts. Sectarian violence persisted against Iraqis as well, with a car parked near a police station by an open-air market exploding shortly after noon in the predominantly Shi'ite enclave of Balad Ruz, in volatile Diyala province of northeast of Baghdad. At least 10 people were killed. Abu Hussein, a 35-year-old elementary school teacher, said the force of the explosion knocked a bag of vegetables out of his hands. He was not injured and so helped to evacuate those who were, flooding the local hospital because they were afraid to take them to facilities in nearby Baqouba, which has become an insurgent stronghold. Gunmen at a fake checkpoint in Baqouba, 56.3 kilometers north of Baghdad, also killed two passengers and wounded eight others when they opened fire on three minibuses that sought to flee from the highway trap. At least 73 other Iraqis were killed or found dead nationwide, including 31 bullet-riddled bodies of men who were apparent victims of death squads usually believed to be run by Shi'ite militias. Meanwhile, Mahdi Army militiamen loyal to radical cleric Muqtada al-Sadr battled with Iraqi troops and local police searching for two militia leaders in the southern city of Diwaniyah as US jets roared overhead. At least three people were killed and 24 wounded, Iraqi officials said. The clashes in Diwaniyah erupted Saturday evening after Iraqi soldiers and police cordoned off a market in search of two senior Mahdi Army figures wanted by US-led coalition forces in connection with sectarian killings. Maj. Gen. Othman Ali, commander of the Iraq army's 8th Division, said his forces captured one of the men, but he escaped when fellow militiamen came to his aid. The fighting on the east side of the city, 128.7 kilometers south of Baghdad, resumed about 9 a.m. Sunday with the support of US jet fighters and helicopter gunships skimming over Diwaniyah's rooftops, police said. Ali said his forces raided two locations in "fierce" fighting that lasted three hours. They didn't find their target suspects, but did find weapons caches at the site, he said. Police and medical sources said 20 wounded Iraqis, including two policemen, were brought to the local hospital from Sunday morning's fighting. The clashes erupted anew around 1:30 p.m, and one soldier and two other people were killed, and three civilians wounded, an army officer said on condition of anonymity, since he was not authorized to speak with the media. The US military had no immediate report on the action. American helicopter gunships also attacked targets in Mahdi Army-dominated Shi'ite east Baghdad late Saturday, killing four suspected militants and destroying 10 rockets, the US military reported. The radical Shi'ite militia is facing growing pressure to bow to central government authority. The US command said an Apache helicopter team was alerted to men setting up multiple rocket firing positions aimed at the Green Zone, home to the US Embassy and Iraqi government offices. Six other suspects were captured by ground forces of the 82nd Airborne Division. A recent increase in mortar and rocket attacks on the US-controlled area has raised concern, especially because they come during the US-led crackdown in Baghdad.