All six were taken to hospitals, but their injuries were minor, the Los Angeles Times reported.
The accident occurred during the afternoon at the Pasadena police heliport, the police department said. Both aircraft were heavily damaged.
One of the helicopters had been on routine patrol and the other was assigned to monitor the USC-UCLA football game at the Rose Bowl.
The National Transportation Safety Board was investigating the crash, the Times said.
2014: The Year in Music [PHOTOS]