BAGHDAD, Iraq - A car bomb exploded today near a Baghdad junior high school for girls, killing six people, and seven American soldiers were killed in two days of bombings in and around Baghdad, the military said.

The U.S. deaths raised the total to 12 Americans killed since Sunday. Those reports came as insurgents carried out a string of explosions, suicide attacks and drive-by shootings around the country that killed 49 Iraqis.

Three U.S. soldiers were killed today in central Baghdad when a car bomb exploded next to their convoy at about 1:30 p.m., said military spokesman Sgt. David Abrams.

The other four were killed Monday after they were attacked in Haswa, 30 miles south of Baghdad, the military said. The soldiers were assigned to the 155th Brigade Combat Team, II Marine Expeditionary Force.

The seven soldiers' identities were not released.

The U.S. military said Monday that three American soldiers were killed Sunday and one wounded in two separate attacks in Mosul, 225 miles northwest of Baghdad. Another soldier was reported killed when his patrol was hit by a car bomb just north of Tikrit, 80 miles north of the capital, and a fifth died in a vehicle accident in Kirkuk.

As of this morning, at least 1,641 members of the U.S. military have died since the beginning of the Iraq war in March 2003, according to an Associated Press count.

The U.S. military announced that a two-day operation involving more than 2,000 Iraqi soldiers and police - the largest joint campaign in Baghdad - had rounded up 428 suspected insurgents.

But insurgents continued to wreak havoc in the capital despite the ongoing crackdown in the Abu Ghraib area, which targets militants believed responsible for multiple attacks on the U.S.-detention facility there and the road linking downtown to the international airport.

Residents called police about a suspicious-looking car parked opposite the Dijlah Junior High School for Girls in Alwiyah, near eastern Baghdad's well-known Withaq Square, a Christian neighborhood. As bomb disposal experts approached the vehicle, it exploded and killed six bystanders, said police Capt. Husham Ismael.

Three civilians and one policeman also were injured. No students were believed to be among the casualties.

"May God seek revenge for those who were killed or injured!" an elderly woman screamed outside a hospital where casualties were brought. "We hope that such killers be killed or perished as they kill our youth. Those killers are against homeland, against Islam."

Militants also gunned down two people and seized control of Tal Afar, a town 50 miles west of the northern city of Mosul, police said today, hours after two car bombs killed at least 20 people there late Monday.

Separately, gunmen opened fire on a four-car convoy carrying conservative Shiite legislator Salamah al-Khafaji, one of the most prominent women in Iraq's new parliament. The lawmaker escaped unharmed, but four of her bodyguards were critically injured.

At least 620 people, including 52 U.S. troops, have been killed since April 28, when Prime Minister Ibrahim al-Jaafari announced his new Shiite-dominated government. Washington hopes his government will eventually train police and an army capable of securing Iraq, allowing the withdrawal of coalition troops.

Iraq's National Assembly convened today, during which a conservative Shiite lawmaker said he was appointed to head a 55-member committee charged with drafting Iraq's new constitution, which must be drawn up by mid-August and put to a referendum by October.

Cleric Hummam Hammoudi, an aide to the leader of Iraq's largest Shiite Arab party, told the AP he was appointed head of the committee and a Sunni Arab and a Kurd were appointed his deputies.

At least 20 people were killed in Monday's deadliest attack when two car bombs exploded near the home of Hassan Baktash, a Shiite Muslim with close ties to the Kurdistan Democratic Party, in Tal Afar, a predominantly Turkmen town of 200,000 people.

Militants today sprayed Baktash's house with machine-gun fire, killing two civilians and clashing with security forces, said Col. Saleh Jamil Sultan.

"Now terrorists have deployed throughout Tal Afar and I consider that Tal Afar is a city that is under the terrorist control," Sultan said.