Baghdad: A suicide truck bombing badly damaged a key bridge north of Baghdad on Tuesday, sending cars plunging into the river and killing 10 people.

Police said that six people were also wounded when the Thiraa Dijla bridge collapsed right after the bomber detonated his explosives-rigged vehicle at a central section.

"Rescue teams are searching for survivors from the cars which went down after the attack," an official said.

Also on Tuesday, the US military said that four soldiers were killed in attacks in Baghdad and Mosul.

Reports say civilians were among those killed in the latest incursion into the Shiite area of Sadr City, but the US military denied this.