Deadly Oil Explosion 'Was Tragic Accident'

Police investigating an oil refinery explosion that killed four maintenance workers have described it as a "tragic industrial accident".

Early indications suggest the blast took place in a vast storage tank as maintenance work was being carried out at the Chevron Refinery in Pembrokeshire last night.

Four contractors were killed and a fifth airlifted to Morriston Hospital in Swansea with serious burn injuries.

The Press Association is reporting three of those who died were male painters while the fourth was a woman on fire-watch duties.

The injured worker remains in hospital in a critical condition.

Witnesses described an explosion so big it shook the windows of a coastguard station across the water, followed by a fireball in the sky over the plant and a dense column of dark smoke.

Police officers were in the process of informing the families of the workers involved as a joint investigation with the Health and Safety Executive began.

Chief superintendent Gwyn Thomas, the officer in charge of the incident for Dyfed Powys Police , said emergency services received a call about the blast at 6.22pm on Thursday.

"The fire was a result of an explosion in a 730 cubic metre storage tank whilst maintenance work was carried out.

"Damage was also caused to an adjacent storage tank."

He added: "Early indications suggest that this is a tragic industrial incident."

Tory MP Simon Hart, who represents Carmarthen West and South Pembrokeshire, said he was "assured that a full investigation" was taking place.

He added: "We live alongside these industrial giants that provide so much work for the county, and few of us think of the risks that come with working there."

Cordons were put up at all access roads leading to the plant, which employs 1,400 people and is one of the largest in western Europe.

Offshore winds dispersed any contaminants released in the blast out to sea and there is not thought to be any ongoing threat from the site to the local area.

The Chevron refinery's general manager, Greg Hanggi, said the accident was "utterly devastating".

"The loss of our co-workers has come as a huge shock to us all," he said.

"Our thoughts and deepest sympathy go out to their families. We will ensure that all employees and contractors are fully supported throughout this difficult time.

"We will take every step possible to determine the series of events that led to this tragic incident and ensure that any lessons learnt from it will be integrated into the business and shared with our industry partners."

The refinery, which processes 220,000 barrels of crude oil a day, was bought by US-based Valero earlier in 2011 for $730m (£458m).

Another $1bn (£611m) was paid for assets including Chevron's petrol stations in the UK and Ireland.

Owen Warrell, who lives four miles away from the site of the blast, told Sky News: "It was just a bit of a pop and a couple of seconds later the house shook slightly.

"When we went outside, over the haven we could see a big plume of black smoke drifting off towards the west."