Dozens of firefighters were called in to tackle a massive blaze at Pickles Auctions on Friday at Bibra Lake, in Perth's southern suburbs.
Smoke billowed from the blaze at the Sudlow Road premises, where dozens of cars stacked three tiers high were on fire, with hundreds more at risk from the fire.
after 5pm, and it took them about three hours to get on top of the blaze.
The full extent of the damage is not yet known.
Some emergency personnel were expected to remain on the scene for hours.
It is believed the business closed not long before the fire broke out, and police say no-one was injured in the blaze.
A smoke alert was earlier issued for people in the area.
An investigation into the cause of the fire is underway.