Firefighters battled the blaze that engulfed the Cootes furniture warehouse at Yenora in Sydney's west, creating a large plume of black smoke that is visible from the city.

Factory fire #fire #guildford #Guildfordfire @newscomauHQ pic.twitter.com/XMXyuXoHFI— Magnus80 (@Magnus80) July 27, 2015

Spot fires may flare up under rubble overnight and it's still too dangerous to enter the building and investigate the cause of the blaze, Fire and Rescue NSW Superintendent Ian Krimmer said.

"We'll be keeping a couple of crews there throughout the night," he said.

"We can't let anyone inside because it's all collapsing in on itself."

Senior firefighters will head to the site on Tuesday and plan how to fully extinguish the fire.

It's understood police are interviewing the factory's owners and workers who were inside when the building burst into flames.

A forklift worker had tried to put out the flames but the fire became too strong, Fire and Rescue Superintendent Selwyn Mathias told reporters at the scene.

"The fuel load of furniture is extremely high ... the fire took hold rapidly," he said.

"Crews were confronted with a huge fire that was totally engulfing the building."

The 135 firefighters at the scene knew the factory couldn't be saved and instead successfully defended neighbouring buildings.

"That was the main priority," Supt Krimmer said.

A motorist who drove past the John Cootes furniture warehouse, on Orchardleigh Street in Yennora, shortly after the fire broke out about 12.30pm on Monday said he could feel the heat radiating into his car, which was about 40 metres away from the blaze.

A large number of emergency service workers attended the scene, and school children and people with breathing difficulties in the area were being urged to stay indoors.

Fire and Rescue NSW had multiple crews just before 1pm. By 2.30pm Fire and Rescue NSW said it had the main fire under control and had managed to protect neighbouring warehouses.

One witness, Rob, told 2GB that the warehouse walls were starting to cave in.

"I drove along Orchardleigh Street. I would have been 40 metres from the loading dock, and I could feel the heat on my car," he said.

"There's nothing going to be salvaged from inside that building; it looks horrific."

Another witness said the flames were shooting about 30 metres into the air and threatening to spread to neighbouring properties in the industrial area.

A number of roads were closed, including Orchardleigh Street.

Massive fire in Guildford/Yennora. Looks like it's near the chemical plant. pic.twitter.com/xqINIqap3H— Baron EH (@Baron_EH) July 27, 2015

*/ ]]>