Fire crews and police were called to the site of the blast this morning and a major incident was declared.

John Kaye reports 20 past 11 Onda major incident Just a quarter of a mile from the M five motorway state, a blast to Tora, part of silo holding biosolids at the Wessex Water sewage treatment works.

There was like a gentle first, followed by an extremely loud exclusion.

This lorry driver had bean delivering goods on was then trapped on a neighboring site.

It sounded like a large collapsed or something.

It was not like to send out before I didn't know what it waas your confusion.

Nobody knew what the situation Waas Emergency teams from six fire stations attended what they described as a very challenging incident.

Tonight it was confirmed that this was no longer a rescue operation.

Sadly, despite the best efforts of all those involved, we can confirm there have been poor fatalities.

This includes three employees of Wessex water on one contractor.

Our thoughts are with the family, friends and colleagues of all those affected in today's instability are the terribly sad incident.

Ah, fifth person has been taken to hospital, but their injuries are not life threatening.

Police say the incident is not believed to have bean terror related on.

There's no risk to the wider public.

When you heard that Jawad was in a warehouse a mile away, when I said straight away, it's explosion because I was in my office and I feel it.

You felt it.

Yeah, it's like shaking.

You know, That must be terrifying.

Yeah, yeah, this is really bad moment for for everyone to work there.

In a statement this evening, Wessex Water described the incident as tragic, saying staff were absolutely devastated.

Tonight.

The prime minister and the mayor of Bristol have both paid tribute to those who died on to the emergency services.

The police have promised a thorough investigation as four families begin to grieve.