Hawthorn units damaged in suspicious fire

A Hawthorn unit block has suffered extensive damage during a suspicious fire.

Residents in the Isabella Grove unit block were evacuated around 2.45am on Tuesday morning.

Police are still searching for one of the occupants of the unit where the fire started, but fire crews are confident nobody has died in the blaze.

MFB Commander Bob Lannigan says the cause has not yet been determined.

Witnesses have reported hearing explosions and a car leaving the block before the fire.