"3 X-RAY 33" END OF WATCH

Police officers from across the country came together at Friday's memorial service for a 22-year-old rookie who had long dreamed of being an officer and was slain just weeks into the job in a Northern California college town. The service for Davis Police Officer Natalie Corona, who was shot and killed last week, will be held at the University of California, Davis. UC Davis said it expects up to 6,000 officers, in addition to family members, friends and members of the public.

Corona's slaying has shocked Davis, which prides itself as a safe, family-friendly community anchored by one of the state's top universities. The last time a police officer died in the line of duty in Davis was in 1959.

Family, colleagues and others who knew Corona have recalled her vibrant smile, compassion, dedication and lifelong dream of being in law enforcement like her father Jose Merced Corona, who spent 26 years as a Colusa County Sheriff's deputy.

A rising star in the department, Corona graduated from the Sacramento Police Academy in July and had completed her field training in December. She was assigned to patrol on her own just weeks ago.

On the evening of Jan. 10, there was no apparent danger when Corona responded solo to the scene of a three-car crash in downtown Davis, near the university campus. But as Corona talked to the drivers involved in the crash, gunfire sounded. Police say gunman Kevin Douglas Limbaugh, 48, was not involved in the crash but rode up on a bicycle and, without warning, opened fire on Corona. He hit her in the neck and fired more shots as she lay on the ground, reloading at least twice as he fired at passing vehicles, narrowly avoiding wounding others before he casually walked home.

Police are still investigating the motive and say Limbaugh did not appear to know Corona or to have specifically targeted her. It is also not yet clear if Limbaugh had planned the attack or acted spontaneously, Davis Police spokesman Lt. Paul Doroshov said.