From BBC:

At least three American soldiers have been killed in an attack on a convoy in the town of Khaldiyah, west of Baghdad, according to witnesses.

According to witnesses, the transport truck blew up after it drove over a landmine or bomb.

French news agency AFP quoted witnesses as saying several soldiers in the vehicle were burnt.

As soldiers tried to evacuate the wounded, they were reportedly attacked with grenades.

"A bomb exploded underneath a troop transport. It caught fire. The remainder of the convoy tried to continue and was hit by rocket-propelled grenades 500 metres [1600 ft] away," Khaldiyah resident Mahmud Ali told the agency.