Chevron Corp said an unspecified hydrocarbon release from the wharf at its Richmond, California, oil refinery has been stopped and a clean up is ongoing, the company said on Tuesday.

The company said a sheen was observed at around 3 p.m. (2300 GMT) on the water near the wharf at the Richmond refinery, which can process 245,271 barrels per day of crude oil.

The spill triggered a health advisory from the Contra Costa Health Department for residents of Richmond, North Richmond and San Pablo, according to local media reports.

"We have issued a community notice and ask the public to remain clear of the area so crews can quickly contain and clean up the released volumes," the company said.