A car bomb exploded Monday in a town northeast of the Iraqi capital while a bus full of Iranian Shi'ite pilgrims was passing. Security officials say five people died and nine were wounded.
The blast in Muqdadiya was the latest in a series of attacks testing the mettle of Iraqi security forces as U.S. troops prepare to end combat operations at the end of August.
Four of the dead were Iranian pilgrims, who have flocked to Iraq's Shi'ite religious sites since the U.S.-led invasion removed Sunni dictator Saddam Hussein in 2003. Saddam banned Shi'ite rites.
The attack comes after bombings and drive-by shootings Sunday that killed at least 10 other people and wounded more than 20.
The U.S. military says an American soldier was killed Sunday during an attack on a patrol in Iraq.
In a statement released Monday, the military said the attack happened in Baquba, but did not give further details.
More than 4,400 U.S. soldiers have died in Iraq since the war began in March 2003.
Other deadly attacks Sunday took place in Babil province, south of Baghdad, and in the northern city of Mosul, where an Iraqi soldier was killed in an attack on a security checkpoint.
Iraqi security forces have been frequent targets of insurgents in recent months as the United States reduces its troop strength in the country.
White House officials said last week the U.S. is on track to end its combat mission in Iraq at the end of August. Fifty-thousand U.S. troops will remain in Iraq to serve as a transitional force. U.S. President Barack Obama has set a goal of removing all U.S. troops from Iraq by the end of 2011.
Some information for this report was provided by AFP, AP and Reuters.