A homicide investigation is underway in Melbourne after a 15-year-old boy was discovered fatally wounded outside a hospital in the city's northern suburbs.

Police were called to Lygon Drive in Craigieburn about 7:50 p.m. Wednesday, where they found the teenager lying face down on the pavement near Craigieburn Community Hospital. A large hunting knife was recovered in the vicinity. Despite efforts to revive him, the boy died at the scene. He has not yet been formally identified.

Investigators are working to determine if the stabbing occurred at or near the hospital, or if the teenager was brought to the location and left there. Detectives remained at the scene on Thursday morning as inquiries continued.

Craigieburn Community Hospital is a public healthcare facility that opened approximately one year ago.

Police are urging anyone who witnessed the incident or has relevant information or footage to contact Crime Stoppers.