Gunman frees pinned-down Vic burglar

A gunman has freed his helmet-stealing accomplice after the thief was chased down and caught by motorcycle shop staff in Melbourne.

The robber stole two helmets from the Bentleigh store on Thursday afternoon but only ran 50 metres down the Nepean Highway before he was caught and pinned down by staff, police say.

Within 30 seconds, however, a silver BMW pulled up beside the group with a man pointing a gun at the shop staff and demanding the thief be let go.