Nine U.S. soldiers were killed and 20 others wounded on Monday in a suicide car bombing against a patrol base northeast of Baghdad, the military said.

The attack took place in Diyala province. The nine U.S. soldiers died of injuries sustained in the blast, the military said.

Of the 20 wounded, 15 soldiers were treated and returned to duty while five others were sent to a medical facility for further treatment, the military said.

More than 3,260 U.S. soldiers have been killed in Iraq since the U.S.-led invasion in March 2003, according to media count based on Pentagon figures.