Aerial footage of Chevron oil refinery fire scene
Aerial pictures of the Chevron oil refinery in Pembroke, on Friday, the morning after the explosion and fire which killed four contractors.
An investigation is under way. Another worker suffered serious burns in the blast at the Chevron refinery, Pembroke, at 1820 BST on Thursday.
Dyfed-Powys Police said the explosion was in a 730 cubic metre storage tank, where maintenance was being carried out.
The plant's general manager called the news "utterly devastating".
The BBC's Wales correspondent Hywel Griffith described the scene on Breakfast News.
03 Jun 2011