BAGHDAD, Iraq, AP – A roadside bomb exploded near a convoy of U.S. troops headed for the Shiite holy city of Karbala on Thursday, and Iraqi police said there were casualties.

Police Capt. Rahim Salho said the attack occurred about 15 miles south of Karbala, as the troops were traveling to assist with the aftermath of a suicide attack. No further details were immediately available, and U.S. officials wouldn’t immediately confirm the report.