Colleagues of four workers killed in a Bristol sewage plant explosion yesterday are in a 'state of shock' after one was blown 500ft into a lake by the force of the blast.
Tributes poured in for the victims who died at Wessex Water Services Ltd in Avonmouth on Thursday morning.
The workers - three employees of Wessex Water and one contractor - were on top of the chemical tank when the blast went off. One other person was injured.
One handwritten note at the scene paid tribute to 'Brian' and said they were thinking of him and those others who had lost their lives.
Trade union Unite has issued a statement which said workers at the site were in shock.
Unite’s regional secretary for the south west, Steve Preddy, said: “We can confirm that Unite has three members working at Wessex Water Services Ltd in Avonmouth.
“We have contacted them and they are, thankfully, uninjured, although in a state of shock.
“Unite will be giving our members maximum support in the days and weeks ahead.
“Unite the union would wish to extend its deepest sympathy to the families of those employees who have lost their lives and as well as those injured in the explosion - our thoughts and solidarity are with all those affected by this tragic event."
The explosion was so forceful it shook nearby buildings, one of the bodies was reportedly discovered 500ft from the chemical tanker.
It blew up at around 11am and also hurt a fifth person whose injuries are not life-threatening.
Witnesses were struck by the magnitude of the explosion - and how the commotion then quickly fizzled out and went eerily quiet.
Sean Nolan, who witnessed the aftermath of the explosion, said: 'It was quite short-lived, I'd say about two or three seconds.
'Sort of a boom and echo and then it just went quiet. That was it. There was no smoke, there was no after-effects of it.'
Keiran Jenkins, who was in a nearby warehouse, said he and colleagues stood rooted to the spot in shock as the walls trembled.
Emergency service crews launched a major operation involving two search and rescue dogs and six fire crews after the blast on the industrial estate off Kings Weston Lane.
A major explosion at a Wessex Water sewage treatment plant near Bristol has left four people dead and one injured, emergency services have said
Witnesses reported a 'loud bang' while others recalled seeing emergency services rushing to the industrial estate
Luke Gazzard (left), Group Manager at Avon Fire & Rescue Service, and Chief Inspector Mark Runacres of Avon and Somerset Police (right) confirmed the four fatalities at a press conference at the site of the explosion this evening
Pictured from the scene appear to show extensive damage to a tank that has been ripped open by the explosion. Workers were understood to have been on the tank at the time of the blast
A witness said earlier 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, two turntable crews and search and rescue dogs as emergency servuces confirmed there have been a number of casualties
Witnesses reported a 'loud bang' while others recalled seeing emergency services rushing to the industrial site earlier today
Chief Inspector Mark Runacres of Avon and Somerset Police told a press conference yesterday night: 'The fire service led the rescue operation but sadly, despite the best efforts of all those involved, we can confirm there have been four fatalities. This includes three employees of Wessex Water and one contractor.
'Specially trained officers have this afternoon made contact with each of the families of those individuals and informed them of the sad news. This is a tragic incident and our thoughts and sympathies go out to them.'
He stressed there was no ongoing public health threat and revealed that the tanks had contained treated biosolids before they are recycled to land as an organic soil conditioner.
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.'
Police confirmed the incident was not terror-related but refused to speculate on the cause of the blast. An exploded oxygen tank has been suggested as a possible cause, but this has not been confirmed.
Wessex Water chief executive Colin Skellett said the company were 'absolutely devastated' by the incident, and said it would be working with the Health and Safety Executive 'to understand what happened and why.'
Pictured: The damage to the chemical tank at the Wessex Water sewage treatment plant where four people have died
One person said on social media they heard a 'loud bang' at the time of the explosion. Pictured: Fire crews at the scene
Mr 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.'
Another witness 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 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.'
Emergency services are at the scene of a large explosion at a warehouse near the recycling facility and water treatment works at Avonmouth
Boris Johnson led politicians in mourning the casualties and pay tribute to the emergency services.
The Prime Minister tweeted: 'Deeply saddened to learn that four people have lost their lives in the water works explosion in Avonmouth.
'Our hearts go out to the victims and their families. Thank you to the emergency services who attended the scene.'
Labour leader Sir Keir Starmer wrote: 'My thoughts are with all those who tragically lost their lives today in Avonmouth. My heart goes out to their friends and family. Thank you to our emergency services for all their work.'
Earlier Home Secretary Priti Patel tweeted she was 'deeply concerned' by the explosion: '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.'
A road leading to the industrial area was closed off this afternoon as emergecy vehicles attend the scene and carried out a rescue operation
The incident happened at the recycling facility and water treatment works at Avonmouth in Bristol, south west England
Home Secretary Priti Patel said she was 'deeply concerned' at news of the explosion in a tweet she posted on social media
Chief Inspector 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
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