An explosion in a storage tank caused a fire at a Chevron oil refinery in Wales on Thursday, killing four contractors and seriously injuring another worker, the company said.
Gwyn Thomas, chief superintendent of Dyfed Powys Police said the fire was caused by an explosion while maintenance work was carried out. Thomas said an investigation into the incident is currently underway and early indications show it was "a tragic industrial accident."
Police did not identify the deceased and Thomas said officers were in the process of identifying next of kin.
Greg Hanggi, the refinery general manager, said in a statement that the loss of the four workers was "devastating."
"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," he said.
A fire department spokesman confirmed that five engines responded to the blaze at around 6:20 p.m. (1720 GMT; 1:20 p.m. EDT). The spokesman declined to give his name, citing company policy.
In March, Chevron agreed to sell the Pembroke refinery along with other marketing and logistics assets throughout the U.K. and Ireland to Valero Energy Corp. for $1.73 billion.
The refinery employs 1,400 people. Chevron Corp. is based in California.