Fire and Rescue NSW (FRNSW) investigators are examining the ruins of a home, destroyed by fire overnight at Emu Plains.
The fire broke out just after 11.30pm on Thursday, September 1 in a single storey house in Nepean Street.
Crews from 12 fire trucks attacked the blaze from three sides as a large column of smoke issued from the property, disrupting traffic on the nearby M4 motorway.
No-one was home at the time of the incident.
A large part of the house’s roof collapsed at the height of the fire, which was extinguished by 3.30am this morning.
Experts from the FRNSW Fire Investigation and Research Unit (FIRU) are now working at the scene to determine what started the fire.