The soldiers were part of Task Force Baghdad, composed largely of troops from the Army's 1st Cavalry Division, U.S. military officials told CNN.

The bomb attack in the evening flipped the 50,000-plus-pound Bradley Fighting Vehicle upside down and into a ditch, Lt. Col. James Hutton, a 1st Cavalry spokesman, told CNN.

Rescue efforts were hampered by flames and secondary explosions, he said.

Similar attacks recently have claimed the lives of Baghdad's provincial governor, and scores of Iraqi police and civilians. U.S. military commanders have said such attacks are aimed at disrupting the elections in Iraq set for the end of this month.

Interim Prime Minister Ayad Allawi has said his government is committed to holding the elections on time.