Four people are understood to have died and one person injured after a huge chemical tank exploded at a sewage works in Bristol.
The casualties are understood to have been workers on top of the tank when it exploded at the Wessex Water treatment works in Avonmouth.
Avon and Somerset Police said three were employees of Wessex Water and one of the victims was a contractor.
A fifth person is understood to have been injured, but their injuries are not thought to be life threatening. Their families of the victims been contacted.
Crews launched a rescue operation involving two search and rescue dogs and six fire crews after the blast on the industrial estate just after 11am.
Luke Gazzard, who led the Avon and Somerset fire service response to the explosion described it as a ‘very challenging incident’.
He added: ‘Our thoughts are with family, friends and colleagues of all those affected by today’s incident.’
An exploded oxygen tank has been suggested as one possible cause, but this is unconfirmed.
Police confirmed the incident was not terror-related but refused to speculate on the cause of the blast.
A major explosion at a Wessex Water sewage treatment plant near Bristol has left several people injured, emergency services have said
Pictured from the scene appear to show extensive damage to a tank that has been ripped open by the explosion
A witness said there was a ‘helicopter looking for missing people’ and police had closed a nearby road leading up to the building
A rescue operation was launched by the fire service, involving five appliances and two turntable crews as emergency servuces confirmed there have been a number of casualties
The major explosion at a warehouse near Bristol (pictured) has left several people injured, emergency services said
Witnesses reported a ‘loud bang’ while others recalled seeing emergency services rushing to the warehouse.
One said they saw ‘at least ten ambulances’ along with police and fire crews heading to the scene, according to Bristol Live.
Jawad Burhan took a photo showing a tank that had exploded and said earlier today there was a ‘helicopter looking for missing people’. Police also closed a nearby road.
He said: ‘I heard the sound, I’m working beside the building in another warehouse. After ten minutes I saw the helicopter coming and the police.’
Wiltshire Air Ambulance said this afternoon that no casualties had been flown to hospital.
Kieran Jenkins, who had been working nearby, said he and a colleague had heard the explosion and seen people running from the scene.
He told the BBC: ‘We were inside the warehouse, the whole warehouse was shaking and we literally stood there in shock.
‘Next thing you know we looked out of the windows and all we could see was people running.
‘We don’t know what happened. It was a bit of a shock really. Fingers crossed nobody was hurt and everything is alright. I heard a bang… we didn’t know what was going on.’
One person working nearby said: ‘All our windows rattled.’ Another added: ‘My better half is working in Avonmouth and their entire building rumbled and shook from it.’
Home Secretary Priti Patel tweeted this afternoon that she was ‘deeply concerned’ by the explosion.
She said: ‘My thoughts are with those affected and our brave emergency services working hard to resolve this incident.’
Darren Jones, MP for Bristol North West, said: ‘This is a serious incident and my thoughts are with those workers who have injured on site today.’
He added: ‘I’m grateful to our fire, police and ambulance staff for their quick response.’
Mayor of Bristol Marvin Rees added: ‘There has been a large explosion at the Wessex Water site on Kings Weston Lane in Avomouth.
‘Thank you to @AvonFireRescue @ASPolice and @swasFT who are doing their very best to help all those involved. My thoughts are with anyone affected by this incident.’
Pictured: The damage to the chemical tank at the Wessex Water sewage treatment plant
One person said on social media they heard a ‘loud bang’ at the time of the explosion. Pictured: Fire crews at the scene
Emergency services are at the scene of a large explosion at a warehouse near the recycling facility and water treatment works at Avonmouth
A road leading to the industrial area has been closed off as emergecy vehicles attend the scene
The incident happened at the recycling facility and water treatment works at Avonmouth
Home Secretary Priti Patel said she was ‘deeply concerned’ at news of the explosion
Chief Inspector Mark Runacres said officers were staying on the scene and were likely to be there for some time as he urged the public to steer clear.
He said: ‘A cordon has been set up and we’d advise members of the public to avoid the area at this time where possible to allow the emergency services to carry out their work.
‘Police enquiries into exactly what happened are at a very early stage and are continuing.’
A statement from Avon and Somerset Police said: ‘A major incident has been declared following a large explosion at a site in Avonmouth.
‘The fire service, police and ambulance service were called at approximately 11.20am this morning (Wednesday 3 December) to a site off Kings Weston Lane.
‘An explosion is believed to have occurred involving one of the chemical tanks at Wessex Water’s Bristol water recycling centre.
‘A rescue operation was subsequently led by the fire service, involving five appliances and two turntable crews and we can confirm there have been a number of casualties.
‘A full investigation into the incident will be conducted.’
Avon and Somerset Police reassured the public that the chemical tank explosion was not a danger to the public.
The silos or tanks are reportedly used to store treated sewage that is dried for use as agricultural fertiliser.
The Environment Agency also confirmed to Bristol Live they will not be investigating the explosion as the blast has not caused a ‘major environmental’ problem.
The force tweeted: ‘We would like to reassure the public there is not believed to be any ongoing public safety concerns following the incident this morning.
‘However, we’d continue to urge people to avoid the area if possible to enable the emergency services to carry out their work at the scene.’
Police have closed the road leading up to the scene – an industrial area on the outskirts of Bristol
Crews from five different fire services were in attendance at the scene after the 11.20am blast
The explosion is understood to have taken place in an industrial area on the outskirts of Bristol
Avon and Somerset Police also reassured the public that the chemical tank explosion was not a danger to the public
Fires from the scene of the explosion (pictured on a Highways England Traffic camera) which took place this morning around 11am on King Weston Lane have been put out, said a fire service spokesperson
Crews from six different fire stations have been sent to the scene of the major explosion
Avon Fire and Rescue Service says there has been a number of ‘casulties’ following the ‘serious incident’ in the Avonmouth area near Bristol
The fire service said it was called at 11.22am and confirmed there have been ‘casualties’.
A statement added: ‘We were called at 11.22am to reports of a large explosion in a warehouse on Kings Weston Lane, Avonmouth.
‘Crews from Avonmouth, Southmead, Yate, Patchway, Hicks Gate, Kingswood, Weston-super-Mare and Temple were mobilised and attended the incident.
‘We were joined at the scene by our police and ambulance colleagues and have now handed over the incident to the police and continue to support our multi-agency partners.’
The fire service said they were aware of ‘casualties’ but could not say how many people had been injured in the incident.
A spokesman for South Western Ambulance Service added: ‘South Western Ambulance Service is responding to a serious incident at premises on King’s Weston Lane, Avonmouth, Bristol.
‘We sent multiple resources to the scene, including land air and other specialist paramedic teams.
Bristol Waste, which run the nearby Avonmouth recycling centre, tweeted that it had closed the site temporarily.
The site is Wessex Water’s largest sewage treatment works, which serves the Bristol area.
A spokesmen from Wessex Water, Luke Gazzard from Avon Fire and Rescue and Chief Inspector Mark Runacres of Avon and Somerset Police will give a press conference at the site at Kings Weston Lane at 5pm today.