The blaze destroyed much of the structure and wiped out items ranging from goal posts and equipment to club clothing owned by the Orange City's senior and junior clubs stored inside the building.

A police statement said the fire was being treated as suspicious.

"The fire caused significant damage to the stadium's seating, roof and storage sheds. A crime scene was established and examined by forensic specialists," it said.

"Investigations are continuing."

Police also appealed for information. "Any residents of the Diamond Drive area with information or CCTV footage are urged to come forward," it said.

Club president Steve Stone said it was a blow to the club after members had contributed to building the grandstand.

"There's heaps of guys who have put a lot of effort into it. It's a disappointment but we'll rally around," he said.

Mr Stone said the club would have to wait for an expert assessment of the structure to see whether it could be saved.

Watch the moment Pride Park was engulfed in flames ...

He said they would also talk to insurance companies to see whether a payout would cover their losses.

"It must have been intense, the fire. All the steel beams are buckled and bent," he said.

Mr Stone said the canteen area had also suffered smoke damage.

Club vice-president Fletcher Niven said the grandstand had been assessed at about $400,000 in a recent valuation.

"I actually built that grandstand," he said.

Mr Niven said the building was covered under the insurance of the adjacent Waratah Sports Club while the stored equipment and supplies were covered under a different policy.

Fire crews rushed to the scene after the fire was reported to emergency services at 2.15pm.

Orange Fire Rescue arrived at 2.21pm, assisted by Rural Fire Service crews and firefighters from Bathurst.

They worked quickly to remove three LPG cylinders from near the flames to avoid the risk of explosion.

Station Officer Dane Philippe said crews took about 30 minutes to extinguish the blaze.

He said structural damage to the roof of the grandstand prevented firefighters performing a thorough investigation of the fire's origins.

"Unfortunately there's an unstable roof structure where the fire went through," he said.

NSW Ambulance paramedics also attended.