Police are investigating a vicious brawl between Collingwood and St Kilda fans during a clash between the two sides at Etihad Stadium on Saturday night.

About 10 men and a small group of women were involved in the out-of-control bar melee which erupted inside the second-floor E.J. Whitten Bar just before three-quarter time.

Video footage captured of the incident shows punches flying between supporters of both football teams, with one man thrown into a wall of memorabilia, while others can be seen wrestling over shattered glass.

Police are investigating a vicious brawl between Collingwood and St Kilda fans.

Fellow supporters can be heard screaming “Knock him out”.