Maccas staff threatened, assaulted in Vic

Three teenagers have been arrested following a violent armed robbery at a Melbourne fast food restaurant.

Police say the trio were arrested just before 11.30pm on Friday night near the Ringwood McDonalds outlet.

Witnesses told AAP two of the group threatened staff with knives, demanded cash and access to the safe.

"One of them punched the manager and kicked one of the workers," they said.

"Then they ran away on foot but one of the customers had called police and they were caught."

Police won't confirm reports staff were assaulted but did confirm claims they were threatened with knives.

The 19-year-old Malmsbury man, 17-year-old Croydon North boy and 13-year-old Jacana boy are yet to be charged.