Fire gutted a house in Koomooloo Crescent, Shalvey on Monday morning.
Police and firefighters were called to the blaze shortly before 7.15am.
Reports of people trapped inside prompted officers to try and enter the premises, but it was judged too risky.
They later found no evidence of anyone inside and it appeared no one was home at the time.
A neighbouring house was also threatened by the fire, but that was contained.
Firefighters got the flames under control within 10 minutes but took almost an hour to completely extinguish any traces of them.
They also discovered some possible asbestos material in the eaves, but said the house appeared to be largely free of the substance.
The house was largely destroyed but no one was reported to have been hurt.
Causes of the fire are unknown, but police have established a crime scene at the premises.
Anyone with any information is urged to contact Mount Druitt detectives on 9675 0699 or Crime Stoppers on 1800 333 000.