There have been “multiple casualties” after an explosion at a waste water treatment works near Bristol.

Avon Fire and Rescue Service said they were called to reports of a “large explosion” on Kings Weston Lane, Avonmouth, at 11.22am.

A spokesman said: “Crews from Avonmouth, Southmead, Yate, Patchway, Kingswood and Temple are currently attending. We can confirm there are multiple casualties on site.

“We are joined by Avon and Somerset Police and the Ambulance service on site. The incident is ongoing.”

Witness Jawad Burhan took a photo showing a tank that had exploded after the blast.

He told the PA news agency there was a “helicopter looking for missing people” and police had closed a nearby road leading up to the building, which he believed was a waste centre.

“I heard the sound, I’m working beside the building in another warehouse. After ten minutes I saw the helicopter coming and the police,” he said.