Updated

Two Army helicopters crashed late Saturday in Baghdad, killing two American soldiers and wounding two others, the U.S. command said. Explosions hit five churches in the capital as violence flared while Iraqi Muslims began marking the holy month of Ramadan.

Also Saturday, the U.S. command said four more American troops and an Iraqi interpreter were killed the day before by car bombs in the west and north of the country.

Mortar shells exploded Saturday near Ibn al-Betar hospital, killing one employee and wounding three others, and in the parking lot of the Mansour Hotel, which houses the Chinese embassy and is home to foreign diplomats and journalists. No one was killed in the hotel attack.

In a sign of hope, community leaders in the rebel stronghold of Fallujah offered to resume peace talks with the government if U.S. forces stop their attacks on the city and free their chief negotiator. However, residents reported explosions late Saturday on the northern edge of the city. The U.S. command had no comment.

The Army helicopters went down about 8:30 p.m. in southwestern Baghdad, the 1st Cavalry Division said. The division said the cause of the crashes had not been determined.

The U.S. military has lost at least 27 helicopters in Iraq since May 2003, many of them to hostile fire, according to figures compiled by the Brookings Institution.

Homemade bombs exploded in quick succession before dawn at the five churches in four separate Baghdad neighborhoods, causing no casualties but further alarming the Christian minority community already on edge over the perceived rise of Islamic militancy following last year's ouster of Saddam Hussein.

In August, coordinated attacks hit four churches in Baghdad and one in Mosul, killing at least 12 people and wounding dozens more in the first significant strike against Iraq's estimated 800,000 Christians since the U.S. invasion began last year.

"It is a criminal act to make Iraq unstable and to create religious difficulties," the Rev. Zaya Yousef of St. George's Church said of the latest attacks. "But this will not happen because we all live together like brothers in this country through sadness and happiness."

No group claimed responsibility for the attacks, which were condemned by the Association of Muslim Scholars, a Sunni clerical group believed to have ties to some insurgents.

"Islam doesn't support the ongoing terrorism," Sheik Abdul Sattar Abdul-Jabbar of the association said.

Three U.S. troops — two soldiers and one Marine — were killed Friday when a car bomb exploded near Qaim, an insurgent hotspot along the Syrian border, the U.S. command said. An Iraqi interpreter was also killed.

A fourth soldier, assigned to Task Force Olympia, died of injuries suffered Friday during a car bombing in the northern city of Mosul, 225 miles north of Baghdad, the U.S. command said Saturday.

U.S. commanders have warned of a possible increase in rebel attacks during Ramadan, when insurgent activity surged last year. Ramadan, the month of fasting and prayer, is marked by greater religious fervor, and some extremists believe they win a special place in paradise if they die fighting non-Muslims during the holy month.

In hopes of preventing rebel attacks, U.S. troops have stepped up military operations in Sunni areas north and west of the capital. The operations included two days of air and ground attacks Thursday and Friday against the main rebel bastion Fallujah.

On Saturday, Fallujah clerics said they were ready to resume peace talks with the government if the Americans suspended attacks and released the city's chief negotiator, Sheik Khaled al-Jumeili, who was arrested Friday.

Talks broke down Thursday because of what the clerics said was the government's "impossible condition" — handing over Jordanian terror mastermind Abu Musab al-Zarqawi and other "terrorists." The clerics said al-Zarqawi was not in the city, a claim that U.S. and Iraqi authorities dispute.

The government had no response to the clerics' offer, and late night explosions suggested military operations had resumed after a daylong lull. Fallujah Hospital officials said U.S. artillery shells fell on a house in Halabsa village, 10 miles southwest of the city, killing a 3-year-old girl and injuring four family members.

Still, the U.S. military said Marines tightened their security cordon around Fallujah, establishing checkpoints to keep suspected terrorists from fleeing the area, about 40 miles west of Baghdad.

Meanwhile, the U.S. military extended the deadline for Shiite militiamen to turn in their weapons in the Baghdad district of Sadr City. Friday had been the deadline for militiamen loyal to radical cleric Muqtada al-Sadr to exchange guns for cash under a deal to end weeks of fighting with U.S. troops there. The new deadline was Sunday, the military said.

Once the handover is complete, the U.S. military will verify that no major weapons caches remain and Iraqi forces will assume responsibility for security in Sadr City. The Americans hope the deal will enable them to focus on the more dangerous Sunni Muslim insurgency.

In other developments Saturday:

— Rocket-propelled grenades struck a joint US-Iraqi military coordination center and a nearby hospital in Baqouba, 35 miles northeast of Baghdad, causing no casualties.

— A member of an ethnic Turkish political group was assassinated in the ethnically tense city of Kirkuk while driving his children to school, police said.

— A video surfaced by a group calling itself the Islamic Brigade that threatened to kill two Turkish drivers unless their company withdrew from Iraq. Insurgents in Iraq have kidnapped more than 150 foreigners in their campaign to drive out coalition forces and hamper reconstruction.

— More than 20 armed men raided a police station in Rawah, some 200 miles west of Baghdad, taking six officers hostage, said witness Fakhry Mohammed Ali, 35. The gunmen released the policemen but blew up the station, he said.

— Also in Rawah, three Iraqi drivers transporting oil to an American base were kidnapped and their tankers set ablaze, Ali said.