The explosion and fire at the Valero oil refinery at Port Arthur Texas was reportedly caused by a fire breaking out at its diesel hydrotreater.
The fire broke out near the plant's fluid catalytic cracker, and the unit suffered severe damage, people familiar with the incident told Bloomberg.
The 243-diesel hydrotreater unit produced about 47,000 bpd. The unit uses hydroge to remove sulphur from motor fuels during the production to comply with US environmental rules.
The refinery, which produces about 380,000 barrels per day, has now been shut down. A few minor injuries were also reported, according to sources.
A Valero spokesperson said all personnel have been accounted for. Two nearby state highways have also been shut down by officials as a precaution, the spokesperson said.
Reports of a boom and smoke coming from the plant 90 miles or 145 kilometres east of Houston, Texas, were seen, 12 News reported. The blast was heard as far as 11 miles away.
The fire at the refinery lasted about 5 hours after the explosion occurred, roughly around 7:30 pm on Monday local time.
The refinery also ran out of water and steam as firefighters tried to put out the blaze.
The plant employs around 770 employees and refines heavy sour crude oil into gasoline, diesel and jet fuel.
The explosion has come amid the global oil crisis casued by the war in iran and the closure of the Strait of Hormuz, a critical chokepoint for a large amount of the world's energy supply.
Gas prices were driven up by the uncertainty over the global supply in the past two weeks.
