In an update issued to media on Monday afternoon, they did say part of the roof of the building had collapsed.

"More than 25 firefighters have knocked down the fire in the Spotlight store in Lamb Street," a Fire and Rescue NSW statement says.

"The neighbouring Bunnings Warehouse and a pizza shop were evacuated as a precaution.

"Part of the roof has collapsed at the main entrance of the store and crews are working to extinguish the blaze completely."

NSW Rural Fire Service and NSW Police are on scene; Fire and Rescue's fire investigation unit is now en route with an accelerant detection dog to try to determine the cause of the blaze.

Fire fighters are battling what's described as a large fire in a business at the Forbes Homemakers Centre.

Some 40 firefighters, Fire and Rescue NSW supported by NSW Rural Fire Service, are on scene, Acting Superintendent Mat Sigmund, Operational Media Coordinator for Fire and Rescue NSW, says.

Mr Sigmund said emergency services were called to the Lamb Street premises just before 2pm and found smoke issuing from the warehouse-style building.

It is understood everyone has been safely evacuated from the business and firefighters have entered the building to fight the blaze.

Mr Sigmund called on people to stay away from the area while firefighting operations are under way.

He also said people living nearby, particularly those with respiratory conditions, should stay indoors as a precaution with doors and windows closed and air conditioning turned off. This is a precautionary measure.

Emergency services are responding to a fire in a major business at the Forbes Homemakers Centre.

Police advise surrounding businesses have been evacuated and urge people to stay away from the area.

More to come as more is known.