The U.S. military in Iraq has sent a team of forensic experts to the northern city of Mosul to investigate the cause of Tuesday's massive explosion at an American military base that killed 22 people and wounded 72 others.

Initial reports said the base's dining hall was struck by either a mortar or rocket. But the military says it is not ruling out anything. The militant group that claimed responsibility for the attack said it was carried out by a suicide bomber.

Among the dead were 14 American military personnel, four U.S civilian contractors and four Iraqi security force members. Most of the wounded were also American servicemen.

Wednesday, the streets of Mosul were deserted and the city's five bridges were closed. American tanks and troops were positioned across the city and helicopters hovered overhead.

Some information for this report provided by AFP and Reuters.