Residents of a unit complex in western Sydney have run for their lives after a suspected arson attack on their building on Tuesday night.

The complex on Halinda Street, in Whalan, was destroyed in the inferno that was raging about 10pm.

NSW Police said nine units were badly damaged by the blaze, which was being treated as suspicious.

Residents were evacuated and there were no reports of any injuries.

Footage shows massive flames licking the night sky as Fire and Rescue NSW crews battled to contain the fire.

Thick smoke shrouded the neighbourhood as the fire ripped through the roof of the building.

The roof caved in on four firefighters who were battling the blaze, reported Channel Seven’s Sunrise.

Nobody was hurt and they were able to continue fighting the flames.

Officers from Mount Druitt Police Area Command established a crime scene and have begun an investigation.

Detectives are urging anyone with information or who may have been in the area at the time to contact police.

Police are also seeking any available dashcam/mobile phone footage.

Contact Mount Druitt Police Station or Crime Stoppers on 1800 333 000.