Smoke on the San Francisco Bay today is part of a drill by ferry and law enforcement officials.
The emergency response drill will take place in an area generally south of the Richmond-San Rafael Bridge. The exercise may be visible from the bridge and Marin, San Francisco, Contra Costa and Alameda counties.
The public could see emergency response vessels and white smoke rising from the scene.
The exercise from 6 a.m. to 5 p.m. today is designed to test the response of many agencies to a security-related event, according to a press release from Bay area transportation officials.
The event will utilize two ferry vessels: the 715-passenger Golden Gate Ferry Spaulding and the 500-passenger Alcatraz Cruises vessel. The scenario to be tested is described as a "mass casualty" drill.