The blaze started at the northwest end of the refinery at about 2 a.m. Although the fire was under control in 60 minutes, firefighters remained at the scene through the morning to monitor the situation, according to KTVU.
Fire crews believe it was a leak in the fuel line that caused the fire, and now Chevron says it's investigating what exactly caused that leak.
It was a small but significant reminder of what happened in 2012 when more than 1,000 residents filed a lawsuit against the oil company after a massive fire broke out at the refinery, blanketing the surrounding neighborhoods with toxic plumes of black smoke. Authorities learned that a vapor leak caused diesel-like gas to spark a fire at Chevron's Crude Unit No. 4, which led to the roaring blaze that lasted well into the night.