Iraq ? A female suicide bomber struck Shiite worshippers in the holy city of Karbala on Monday, an official and a witness said, killing at least 43 people and leaving pools of blood on the street leading to one of Iraq’s most revered mosques.

The blast was the deadliest in a series of attacks that left at least 72 Iraqis dead, including six youths killed when mortar rounds slammed into a soccer field in eastern Baghdad.

Two U.S. soldiers also were killed Monday in a roadside bombing north of Baghdad, bringing the American death toll closer to 4,000 as the U.S.-led war enters its sixth year. At least 3,990 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 violence marred overlapping trips by Vice President Dick Cheney and Sen. John McCain to Baghdad. Their visits were aimed at touting recent security gains and stressing Washington’s long-term commitment to fighting insurgents in Iraq.