An officer was injured when riot police were pelted with rocks while arresting six African-Australian youths at Sunshine railway station on Thursday night.

Authorities were alerted to a large gathering of youths at the train station just before 10:30pm.

Stills from a video showing a brawl between two gangs in St Albans on Christmas Eve.

Police believe the six males arrested were involved in affray and robbery offences in St Albans, in Melbourne's west, over the past two weeks.

As police were detaining them other teenagers at the station began throwing rocks, injuring one officer from the Public Order Response Team.