A federal officer attempting to break up an altercation during a pro-Israel demonstration Sunday at the federal building in Westwood fired a single shot but no one was harmed, Los Angeles County sheriff's officials said.. The rally, which drew some 500 people, was breaking up about 5:45 p.m. when Israel supporters and pro-Palestinian protesters began to clash, said sheriff's Deputy Juanita Navarro. An officer with the Department of Homeland Security sought to intervene and fired his weapon once, Navarro said.