Police and emergency services responded to a shop fire in Glenroy last night.
The blaze is believed to have started in a house at the rear of the Widford Street premises about 10pm.
Emergency services were alerted to the fire by a man who resided at the address.
A second man, who was also living at the address, was conveyed to hospital with life-threatening injuries..
The exact cause of the fire is yet to be established, however it is being treated as suspicious.
A crime scene guard will remain overnight with an arson chemist expected to examine the scene in the morning to determine how the fire was started..
Anyone with information is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential report online at www.crimestoppersvic.com.au