Schoolie knocked out in brutal one-punch attack

Shocking video has emerged of a teenager being knocked out in a vicious one-punch attack in Surfers Paradise.

The video was shot about 3.15am today on Orchid Avenue and shows three men kicking the victim in the legs before he is punched to the ground.

9NEWS understands the victim was unconscious for a few minutes and was left bleeding from the head before being transported to Gold Coast University Hospital for treatment.

The victim is understood to be an 18-year-old Schoolies reveller who was visiting the Gold Coast from New South Wales.

A friend has told 9NEWS the teenager was targeted after sticking up for a group of women who were being harassed outside a bar.

Police are investigating the incident but no formal complaint has been made and no charges have yet been laid.