POLICE are investigating how an 18-year-old sustained severe burns at a party in Collaroy Plateau.

Police were told the man was with friends at a party on Essilia St when he allegedly agreed to be set alight with aerosols and flammable liquids about 12.20am.

Police said the man was taken to Royal North Shore Hospital where he was treated for “superficial but excessive burns to his back”. He remains in a stable condition.

Officers arrested an 18-year-old man at the scene and he was taken to Dee Why Police Station for questioning. Investigations are continuing.

On the same night in the Sydney CBD, a man was left bloodied on the pavement on George St.

Police and private security guards dealt with the matter and handcuffed the man for a time but no arrests have yet been made.