Around 3.30am, five people forced entry into a home on Rockleigh Street, Thornton, waking the occupants.
The group – four men and one woman – locked themselves in a room before ransacking it.
When confronted by the occupants, a man and woman fled the scene with stolen property.
A male occupant confronted the men still in the room, when he was struck to the head with a crow bar.
Following a struggle, the rest of the group fled.
A 19-year-old man was treated for facial injuries and taken to Maitland Hospital in a stable condition.
Anyone with information is urged to contact Crime Stoppers.