Captain Ty Wilson of the 1st Armoured Division said a makeshift bomb, possibly a mortar round detonated by remote control, exploded at dawn on Saturday, on an exit ramp off a highway in the southwest of the capital.
Wilson said the bomb, placed beside a steel guard rail under a tree, had hit a Humvee military vehicle.
In another major incident, eleven members of a martial arts team were wounded, three of them seriously, when unknown gunmen opened fire on their bus near the northern oil town of Kirkuk.
The Kurdish Taekwondo team was heading back to Kirkuk from a Baghdad tournament when they came under attack.
Doctors said that three of the team members were in serious condition and have been operated on five times.
Several other attacks were also carried out across Iraq in the past 24 hours, targeting either the US forces or Iraqi police, Aktham Sulaiman, Aljazeera correspondent in Iraq, reported
“An Iraqi police station came under a series of attacks in the city of Mosul”, he added.
According to Sulaiman, “a 20kg explosive device was found in Baghdad’s Press Association building”.