A major incident has been declared following an “explosion” at an industrial estate in South Wales.

Flames and smoke were seen after the fire broke out in Severn Road, Treforest, on Wednesday evening.

Local NHS emergency departments are on “high alert” after the blaze, with people asked not to attend A&E unless “absolutely necessary”.

South Wales Police said: “We are at the scene of a serious incident on Severn Road, Treforest.

“The roads around the industrial estate are currently closed and are expected to remain as such for some time.”

Cwm Taf Morgannwg University Health Board said: “Due to the ongoing incident at Treforest Industrial Estate this evening, all of our emergency departments are currently on high alert.

“Please help us by not attending A&E unless absolutely necessary. We need to be able to provide care to those who need it the most.”

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.”