WARNING DISTRESSING: A teenager has been charged after a disturbing video of a security guard being kicked in the head a Perth underage festival was posted on Facebook over the weekend.

The incident allegedly took place at the Perth Good Life festival at Claremont Showgrounds at 6:30pm, just two hours after the underage festival began in front of hundreds of spectators.

View photos A teenager and security guard can be seen wrestling on the ground as bystanders watched. Photo: Facebook More

Detectives charged an 18-year-old Hazelmere man with assault occasioning bodily harm and trespass on Monday afternoon.

He is due to appear in Perth Magistrate's Court on Wednesday, March 16.

In the video, a young man can be seen wrestling on the grass with a security guard.

Soon after, another teenager in a white shirt charges over, kicking the man directly in the face, sending out a loud crack as bystanders gasp in horror.

The security guard - believed to be aged in his late 40s to early 50s - is knocked out by the vicious blow, his body becoming limp as he slumps face forward onto the ground.

The first wrestling teenager becomes free from the guard's grip after the kick, before he also punches the guard while grabbing his bag and fleeing the scene.

The security guard is left lying helplessly on the ground.

View photos This is the moment after a teenager in a white shirt (not shown) kicked the security guard in the head, leaving him slumped on the grass. Photo: Facebook More

A teenage girl can be seen checking on the slumped guard before he attempts to rise on his hands and knees.

Woody Woodford shared the violent video to his own Facebook page with one simple message, which is for people to "stand up" and "make the change".

"How can people stand their [sic] and record your just a weak as the bloke kicking security in the head. Out of everyone who was there I can't believe no one helped during or atleast tried to stop the bloke. All this generation knows how to do is record....... Stand up make the change it only takes one person to make a difference!” Woodford posted.

Shocked bystanders filmed the vile attack from multiple angles, uploading other angles to the Most Wanted Lads Facebook page.

"Do people not realise what a small hit to the head can do? Let alone a big one? Has no one learnt from the 'one hit can kill' campaign?" one user wrote.

View photos The security guard attempts to pick himself up off the ground. Photo: Facebook More

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