From the San Francisco Chronicle:
Six Bay Area counties announced a “shelter in place” order for all residents on Monday — the strictest measure of its kind yet in the continental United States — directing everyone to stay inside their homes and away from others as much as possible for the next three weeks as public health officials desperately try to curb the rapid spread of coronavirus across the region.
The directive begins at 12:01 a.m. Tuesday and involves San Francisco, Santa Clara, San Mateo, Marin, Contra Costa and Alameda counties — a combined population of more than 6.7 million. It is to stay in place until at least April 7. Three other Bay Area counties — Sonoma, Solano and Napa — were not immediately included.