The fire began at 6:15 p.m. in the No. 4 Crude Unit at the Richmond refinery. Officials say workers noticed a leak and called for an inspection team. They realized it was a serious problem so they evacuated the unit and that's when the leak ignited.
The plume of black smoke and flames could be seen in many parts of the Bay Area.
Residents in Richmond, North Richmond and San Pablo were ordered to shelter in place and a health advisory was issued for several more nearby cities. Additionally, the Contra Costa County Public Health Department recommended that anyone who smelled smoke stay inside and close all windows and doors and turn off air conditioning units. The shelter-in-place was lifted at 11:15 p.m.
A number of people showed up at the Kaiser Permanente Medical Center in Richmond. Many were still waiting to be checked out late Monday night.
Oakland police issued a community advisory as the plume of smoke headed for the North Oakland hills.
Several East Bay BART stations were closed throughout the evening. The last reopened at 11:30 p.m.
Refinery general manager Nigel Hearne apologized for the incident and said Chevron was working with government agencies to determine the exact cause of the fire.
"As you can see, we've made significant progress, and we're still in the process of controlling the fire," Hearne said.
Although several nearby residents said they heard explosions, Hearne denies that.
"I was in the area, actually I was at the other end of the refinery, I did not hear an explosion," he said. "So I don't know where the four explosions you heard came from."
With relatively no winds, the plume climbed high and didn't dissipate -- a good thing for air quality. Officials from the Contra Costa County Public Health Department and the Bay Area Air Quality Management District area continuing to take air samples, but according to their measurements they have not picked up any harmful readings.
One refinery employee sustained a minor injury and was treated at the scene.
The last time this refinery had an incident this significant was in January 2007.
Chevron will hold a community meeting Tuesday for neighbors with questions. It is scheduled for 6 p.m. at the Richmond Memorial Auditorium.