Emergency services were called to Victoria's maximum security prison on Monday night after a fight broke out among juvenile detainees.

A source told Fairfax Media that a group of teenage offenders at the Barwon Prison's Grevillea unit started fighting about 7:45pm.

The source said staff intervened in the fight, and the inmates started to attack them.

The fight involved a group of 17-20 youths, according to AAP.