Terrifying footage shows helicopter spinning out of control and crashing on California beach

Horrifying video shows the moment that a helicopter spins out of control before crashing into a beach in California.

The helicopter, a Bell 222, can be seen hovering above Huntington beach in California at a low altitude and manoeuvring at around 2pm ET on Saturday.

Then in a terrifying moment the aircraft suddenly begins to spin chaotically in the air and make a stomach-churning lurch.

Finally, to the horror of onlookers, the aircraft suddenly plummets from the sky and comes to rest in some trees just off the beach.

Witnesses rushed towards the stricken vehicle, which was suspended on the tree trunks.

The force of the blades as the helicopter came down was so powerful it appeared that two palm tree trunks were completely severed in the crash.

The moment the aircraft begins to spin (YouTube/9NewsAUS)

It's not clear what caused the helicopter to suddenly begin spinning.

Footage from a different angle shows something flying off it just seconds before it hits the ground.

Some readers may find the below footage distressing:

The Huntington Beach Fire Department have since confirmed that the helicopter was linked to the upcoming 'Cars 'N Copters' event which had been scheduled to take place at the beach over the weekend.

Beachgoers had been watching helicopters land ahead of the public display when the incident happened, with witnesses rushing for cover when it became clear that the pilot had lost control.

Two palm tree trunks were severed by the blades (YouTube/9NewsAUS)

One eyewitness told 9 News Australia: "People were saying it's going to explode it's going to catch fire, back up, get away."

Miraculously, it appears that no-one was fatally injured in the crash at the time of writing.

Five people were taken to hospital with injuries after the crash.

Of these, three were people who were injured on the ground including one child, and two were pulled out of the wreckage.

An investigation is now underway over what might have caused the helicopter to begin spinning so erratically while performing a seemingly simple manoeuvre.

It's not clear at present, but the clip shows just how quickly the aircraft begins to spin.

The Federal Aviation Administration and National Transportation Safety Board have been notified of the crash.