Something went down Monday morning at the Chevron refinery in Richmond, and it led to some flaring — the practice of safely burning excess hydrocarbon gases that comes with dramatic flames shooting out of smokestacks and the release of smoke.

The first flaring occurred at 4:45 a.m., as the Chronicle reports, at which point there was an evacuation of "fewer than 100 people." ABC 7 reports that those people were all Chevron employees, and the evacuation was done as a precaution. The company said in a statement that workers had identified the problem that prompted the flaring, and were working to solve it.

A second flaring occurred around 9 a.m., per the Chronicle, sending black smoke billowing over the Bay.

The Mercury News reports that there was a "process upset" at the refinery, and in a report from the California Governor’s Office of Emergency Services, investigators are looking into "the release of an unknown amount of hydrogen sulfide into the air." The Richmond Fire Department reportedly stated that the refinery had had a "compressor failure."

Area health officials have said there were no reports of unusual smells, but these flaring incidents tend to cause some mild public panics in the East Bay.

One particularly dramatic example occurred in December 2014, leading to subsequent calls for an investigation.

Back in October 2019, in nearby Crockett, a couple of fuel tanks exploded at the NuStar refinery, leading to a small grass fire and the closing of I-80 in both directions.