A Victorian youth justice centre is in lockdown after three prison officers were assaulted by detainees in a violent brawl.

Police and emergency services were called to the centre following reports of a fight at the Malmsbury Juvenile Justice Centre about 2.45pm on Sunday.

It is believed three prison officers were punched and kicked by inmates during the incident.

A prison source said the guards required medical treatment, one for serious facial injuries, after the attack.