Iraqi police say two bomb blasts in Baghdad have killed at least seven people and wounded about 20.

In the first attack, a bomb exploded on a minibus in the central Karradah district Sunday morning, killing six people. About 45 minutes later, a car bomb went off in eastern Baghdad, killing one person.

In another development, the U.S. military says about 3,200 American troops from the 82nd Airborne Division have arrived in Baghdad to help Iraqi security forces combat sectarian violence.

The brigade is to be fully operational by February 1. The reinforcements are the first to be deployed to Baghdad as part of President Bush's new strategy to stabilize the city.

Elsewhere in Iraq, the British military says a roadside bomb killed one British soldier and wounded three others today near the southern city of Basra.

On Saturday, 19 American troops were killed in Iraq, including 12 on a Blackhawk transport helicopter that crashed northeast of Baghdad.

The U.S. military revised the death toll Sunday down from 13. The military is investigating the cause of the crash, which killed everyone on board the aircraft.

Saturday was one of the deadliest days for U.S. forces since the war began in 2003.

Five American soldiers were killed in the Shi'ite holy city of Karbala as militia fighters attacked a provincial government building with grenades and small arms.

U.S. spokesman Brigadier General Vincent Brooks says the attack occurred as American and Iraqi military officials were meeting to discuss security arrangements for pilgrims arriving in Karbala for a Shi'ite festival, Ashura.

The U.S. military says another two American soldiers were killed Saturday in roadside bombings.