Police are investigating an armed robbery at a supermarket in Oakleigh South this afternoon.

Police have been told two males entered the rear of the Macrina Street supermarket just after 3.30pm.

It’s alleged one of the offenders armed with a firearm approached the attendants at the front counters before demanding cash.

They fled the scene heading east along Ferntree Gully Road with a substantial amount of cash.

Both offenders are described as being aged in their late teens to early 20s, Caucasian in appearance and one of the men is described to have an olive complexion.

The first offender was wearing a blue t-shirt with a white t-shirt covering his face.

The second man was wearing shorts and a t shirt over his face