A car bomb exploded Monday in western Mosul as an American military convoy was passing, witnesses said. First reports indicated it may have been a suicide attack. Capt. Angela M. Bowman, a military spokeswoman, said a coalition patrol was involved in a "complex attack," but details were still under investigation. Initial reports indicated there were casualties, she said, but no immediate figures were available. Witnesses said U.S. forces cordoned off the area soon after the attack.