BAGHDAD, April 2 -- At least 50 people were killed Sunday in Iraq in a catalogue of violence that included a mortar attack, military firefights, roadside bombings and other explosions.

In addition, the U.S. military reported the deaths of six soldiers and airmen, including two who were killed when their helicopter apparently was shot down during a combat air patrol southwest of Baghdad on Saturday.

"Military officials believe the crash was the result of hostile fire," the military said in a statement, adding later that the remains of the pilots of the AH-64D Apache Longbow attack helicopter were recovered late Sunday.

In the single deadliest incident, at least nine people, including three women and two children, were killed in a mortar barrage in the southern Baghdad neighborhood of Dora, a predominantly Sunni Arab area, according to Baghdad police Col. Abdullah Nuaimi. Fifteen people were wounded in the attack, he said.

The bodies of 10 men, all blindfolded and with their hands tied in front, were found Sunday morning in three areas of western Baghdad, Nuaimi said. All of the men had been shot.

About 40 miles north of Baghdad, in the village of Gubba, insurgents blew up a Shiite Muslim mosque, leaving it in ruins and killing a guard posted inside, Baqubah police Lt. Col. Adnan Lafta said.

The killings and attacks, which appeared to target specific religious communities, are the sort that military and political analysts say are being used by sectarian and insurgent groups to foment strife between Iraq's Sunni Arabs and Shiite Muslims and push the country toward civil war.

The U.S. military also said two U.S. soldiers on foot patrol were killed by a roadside bomb in central Baghdad on Saturday. A Marine died from wounds sustained during combat Friday in Anbar province, a stronghold of Sunni insurgents west of the capital. And a soldier died of injuries sustained Thursday in a non-battle related operation in the northern city of Kirkuk. No other details were available.

In other areas of the country Sunday, five people, including three children, were killed when a firefight erupted in Ramadi, an insurgent hotbed 60 miles west of Baghdad, after a U.S. military Humvee was struck by a roadside bomb, witnesses and a hospital official said.

The witnesses, who spoke on condition of anonymity, and an inspection of the scene indicated that there were U.S. casualties.

A doctor at Ramadi General Hospital, Thamir Aisawi, said that fighting erupted after the Humvee was hit by a roadside bomb while traveling through the center of town and that the soldiers inside scrambled out to defend themselves. As they huddled near the vehicle, insurgents attacked them, and the soldiers returned fire in what witnesses described as a random manner, leading to the civilian casualties. The soldiers were subsequently evacuated from the scene.

Omar Felaih Al-Rawi, 30, who owns a store near the spot where the explosion occurred, said a roadside bomb was "planted by al-Qaeda elements this morning and was waiting for an American convoy to pass. They detonated it on an American patrol, which led to completely destroying a Humvee, killing and injuring those who were on it."

A U.S. military spokesman said he had no information about the incident.

Nuaimi, the police official, said a mother and five of her children were killed in a large explosion at their house southeast of Baghdad. The father was not at home at the time of the blast, he said.

Police were investigating whether the family of Shiite Muslims was the target of the blast or whether the father may have been storing an explosive device in his home, Nuaimi said.

Late Saturday in southern Iraq, British and Iraqi soldiers detained 14 members of the Mahdi Army, a militia loyal to Shiite cleric Moqtada al-Sadr. Four were later released.

"They were brought in on suspicion of serious crimes and terrorism in and around Basra city," said Maj. Sebastian Muntz, a spokesman for the British military. "Ammunition and weapons were found there, which gave us a good indication that these are the correct people being detained."

Previous detentions of Sadr loyalists, whom the British consider among the biggest threats to stability in the area, have sparked protests and other unrest. In response to Saturday's detentions, the Mahdi Army issued threats against British and Iraqi forces.

Correspondent Jonathan Finer and other Washington Post staff contributed to this report.

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