Federal officials are investigating a collision involving two police helicopters in the Los Angeles area that left five officers and a civilian with minor injuries. Investigators believe Saturday's crash occurred when the rotator blades touched of a chopper that was landing and one that was taking off, Lt. Phlunte Riddle said. The collision caused extensive damage to both aircraft, crumpling the tail and breaking the blades of one and causing the blade to fall off and other damages to the other. The injured were taken to hospitals for evaluation after the 4 p.m. collision at a helipad in Altadena. One of the observers was a civilian. The FAA and the National Transportation Safety Board were investigating.