The explosion comes amid a spike in gas prices driven by uncertainty over the global oil supply because of the Iran war. The refinery has about 770 employees and can process about 435,000 barrels of oil per day, according to Valero's website. The plant refines heavy sour crude oil into gasoline, diesel and jet fuel. Images and video posted online show a large plume of smoke and flames billowing out from the refinery. Some residents reported hearing a loud boom and seeing their windows shake.