Oil major Chevron said on Friday that four people were killed and one person was seriously injured in an explosion at its refinery in southwest Wales.The blast occurred at the 220,000 barrel per day Pembroke refinery on Thursday. Chevron did not provide any details on the operational status of the refinery.
Police said a fire broke out after an explosion in a storage tank during maintenance. An adjacent storage tank was also damaged.
"We will take every step possible to determine the series of events that led to this tragic incident," Chevron said.
Chevron put the refinery up for sale last year to lower its exposure to the refining business.
U.S. refiner Valero Energy Corp agreed in March to buy the refinery and other assets in a $730 million deal expected to close in the third quarter.