RICHMOND, California (Reuters):

A fire at a Chevron refinery in Richmond, California, on Monday sent flames leaping as high as 100 feet, but was not expected to affect production, company and emer-gency officials said.

"It looks like the fire is contained to a small area in the crude unit," which is where the fire started, said Tony Semenza, executive director of Contra Costa County's emergency response.

A worker was treated at a local hospital for first-degree burns and released, said Chevron spokesman Walt Gill.

A notice Chevron filed with the California emergency services office said the flames broke out at the refinery's No. 4 crude unit. The refinery area overlooks a scenic area of the San Francisco Bay to the east of San Francisco and north-west of Berkeley and Oakland.

Nearby toll collectors at the Richmond Bridge, which links to Marin County, were evacuated as a precaution as drivers were allowed a rare free trip over the bridge, said Merlin Turner, battalion chief for the Richmond Fire Department.

He added that Coast Guard and other officials were monitoring the air for the presence of possible dangerous chemicals.

The Chevron Richmond refinery, which is more than 100 years old, has a production capacity of 243,000 barrels per day. The refinery began shutting down units for an annual overhaul on Friday. According to Semenza, Monday's fire started in a unit that was being shut down.