South Wales Police said roads around Severn Road in Treforest are expected to remain closed for some time due to the "serious incident".

Local councillor Karl Johnson told Sky News he believes the incident happened at Mindset Functional Fitness Ltd, with the front of the building "completely destroyed" and a nearby car dealership also potentially affected.

More than 15 police cars and 10 ambulances have been deployed to the scene, with support from the fire service, Mr Johnson said.

Fellow councillor Andrew Morgan said on X (Twitter) that "there is a significant fire on the Treforest Industrial Estate, emergency services are on the scene... please avoid the area".

Local NHS emergency departments are on "high alert" due to the incident, with people asked not to attend A&E unless "absolutely necessary".

Rhondda Cynon Taf-based radio station GTFM reports that a listener had called in after hearing "a loud explosion which seems to have triggered a large fire".

Wales Online quoted witnesses as saying they heard a "massive bang" which shook houses, with one adding: "Must have been a big explosion."

Heledd Fychan, Welsh Senedd member for South Wales Central, has described the images and reports of the incident as "hugely concerning" - and urged people to heed warnings to avoid the area.

Jonny Foxhall, 36, the owner of nearby music venue, Green Rooms, told the PA news agency: "Our front door was flung open so we went out to see what had happened.

"We could see a smoke cloud and an orange glow from above the treeline quickly followed by flames."

He added: "To feel the shockwave from the explosion is something I've never experienced before."

Bus operator Stagecoach South Wales has said its 132 and 120 services are unable to serve Rhydfelin and Hawthorn on their return journey due to the incident.

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