Photo: vicpolicenews.com.au

It is believed a 33-year-old man and 37-year-old woman, both from Reservoir, received stab wounds following a physical altercation with an unknown male about 4.20am.

The pair was approached by a group of four people outside a convenience store when an argument broke out over a mobile phone.

The male victim was taken to hospital where he underwent surgery and is currently in a serious condition.

The female victim was also taken to hospital and she is in a stable condition following surgery.

Police arrested four people for questioning but they have since been released and are being treated as witnesses.

Melbourne Crime Investigation Unit detectives have released CCTV footage and are hoping to speak to anyone who may have witnessed the incident or has further information.

The offender is perceived to be Caucasian in appearance and 178cm tall with a medium build.

He was wearing a grey hoodie, grey baggy pants and sneakers, and was carrying a backpack and duffel bag.

Anyone with any information is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential crime report at www.crimestoppersvic.com.au.