Less than 12 hours after a sniper killed several police officers in Dallas, three dozen fresh-faced recruits sat solemnly in dark-blue uniforms outside the Los Angeles Police Department's downtown headquarters, staring straight ahead during a graduation ceremony marking the end of their journey to become fully-fledged cops. "Today was supposed to be a happy day," L.A. Mayor Eric Garcetti told them. "But we come here today with tears in our hearts, with hearts that are broken." Thursday night's attack in Dallas hung over the LAPD's graduation ceremony Friday morning, the pomp and circumstance clouded by concern. One veteran officer's eyes welled with tears as he talked about the attack.