Two suicide car bombers struck Syria's army command headquarters Wednesday in Damascus, killing four guards and engulfing a key symbol of President Bashar Assad's embattled regime in flames, state media and witnesses said. The twin blasts were followed by several hours of gunbattles between rebel fighters and regime forces in downtown Damascus. A reporter for an Iranian TV channel was killed by gunfire near the clashes, and a correspondent for another Iranian station was wounded. The brazen rebel attacks in the heart of the Syrian capital highlighted their determination to bring down Assad as the country's civil war intensifies. It was the second day of bombings to shake the capital. A Damascus school that activists said was being used by regime forces as a security headquarters also was bombed on Tuesday, wounding several people.