WASHINGTON - A law enforcement official says police are investigating letters sent to Capitol Hill offices showing pictures of a Times Square military recruiting station that was bombed. According to the official, who was briefed on the investigation, the letters included words to the effect of, "We did it." The official did not know which offices received the letters. The small bomb caused minor damage to the New York military recruiting station before dawn Thursday and police were searching for a hooded bicyclist seen on a surveillance video peddling away.