Los Angeles (CNN) -- A Los Angeles Police Department helicopter had to make an emergency landing Sunday morning after a gunman opened fire on the chopper, authorities said.

The helicopter landed safely and the pilot and observer on board were not injured, said police Detective Gus Villanueva.

The incident occurred in the Van Nuys area, when police got a call at around 6 a.m. local time (9 a.m . ET) of shots being fired, police said. The helicopter was responding as backup to a patrol car dispatched to the scene.

The helicopter was at the Van Nuys airport after the incident, and was to be put on a flat-bed truck to be towed downtown for investigation and repair, authorities said.

The apparent shooter eventually was subdued by his family members, Villanueva said. A semi-automatic rifle was recovered, he said.

Police got multiple calls that a second gunman was involved, and a search was conducted Sunday afternoon, Villanueva said. That search was called off later, Villanueva said.

CNN's Greg Morrison contributed to this report.