Footage has been released of the moment two police helicopters were completely destroyed - injuring five officers and one civilian in California when the rotor blades collided.
The incident happened in November 2012 on the heliport of the Pasadena Police Department as one helicopter was flying in and another was getting ready for takeoff.
Surveillance video of the horrific crash was only recently released showing the moments leading up the crash.
The Bell OH-58 helicopter is seen being pulled on to the pad by three men.
As the pilot prepares for takeoff, a second Bell OH-58 returns to the pad.
The pilot in the second helicopter manoeuvres the aircraft on to the pad when its rotor blades strike the first helicopter's blades.
The collision causes the rotor blades to rip apart and fly in different directions.
Both aircrafts are destroyed leaving debris scattered across the heliport pad.
A man who was standing on the heliport pad at the time of the crash is knocked to the ground.
He jumps up and sprints away from the wreckage towards safety as the pilots from both helicopters climb out of their severely damaged helicopters.
Police said six people were injured in the November 17 crash, including five officers aboard the helicopters and the civilian who had been standing on the heliport pad. They were all hospitalised with minor injuries and released.
Pasadena Police Chief Phillip Sanchez told NBC at the time that the returning helicopter had been monitoring traffic for the Rose Bowl and came back to the heliport pad because of weather conditions.
The other helicopter was getting ready to takeoff and respond to a call in the area.
Sanchez told the outlet that it was the first time police helicopter rotor blades had collided causing an accident.