Police are investigating an armed robbery at a fast food restaurant in Laverton North this morning.

Investigators have been told three or four masked men brandishing weapons entered the Little Boundary Road premises via the staff entrance just after 1.30am.

A 19-year-old male store attendant was struck to the head with a blunt instrument before one of the men threatened a female store attendant with a knife, demanding cash.

The bandits fled the scene with an amount of cash in a white Holden Commodore sedan.

The male store attendant was conveyed to The Alfred hospital with serious head injuries, believed to be non life-threatening.

The female store attendant was not injured.

There were no customers in the store at the time of the incident.

Police are appealing to anyone with information about the armed robbery to contact Crime Stoppers on 1800 333 000 or visit www.crimestoppers.com.au.