An investigation has been launched following an explosion and fire at an oil refinery which claimed the lives of four workers last night.

Firefighters were called at 6.22 pm last night following a blast and subsequent fire at Chevron Oil Refinery, in Pembrokeshire.

According to the BBC, another worker suffered serious burns in the explosion.

Specialist fire appliances were also mobilised including two foam vehicles, a chemical incident unit, environment unit and a control unit.

A 730 cubic metre storage tank had exploded while maintenance work was being carried out. Damage was also caused to an adjacent storage tank.

Speaking last night, chief superintendent Gwyn Thomas, from Dyfed Powys Police, said:

"Crews from Mid and West Wales Fire and Rescue assisted the onsite Chevron fire personnel throughout the operation. The fire itself was extinguished quickly and the crews worked to make the scene safe for Police to start their investigation.

"We can confirm that any material released into the atmosphere as a result of the blast were immediately dispersed. The wind was blowing off shore, away from residential areas. Members of the public can be reassured that there is no ongoing risk to health as a result of the incident."

Quick response praised by Buncefield chief
Firefighters, who managed to put out the fire within an hour and a half, were praised by Roy Wilsher, who was the fire officer in charge at the 2005 Buncefield refinery fire.

Speaking to info4fire this morning, the operations director for the Chief Fire Officers Association said: "This was a tragic incident but firefighters responded exactly the way we would expect and the fire was out after an hour."

When asked about whether lessons had been learned from Buncefield, he said: "It would be arrogant to say so, but Buncefield has helped to add to our knowledge about how to tackle industrial fires."

There have been several incidences at the plant, including an explosion and fire in 1994 which injured workers.

Mr Wilsher, talking about Chevron's safety record, said: "I'm not sure whether we could ever say a plant processing volatile materials is 100% risk free, but we are certainly moving as close as we can."

He said he expected the investigation to take a shorter time to conclude than the one taken for Buncefield, because of the comparatively smaller scale.