Six counties in the San Francisco Bay Area — about 6.7 million people — are under a “shelter in place” order to try to stem the spread of the novel coronavirus, the Los Angeles Times reports.

The order will go into effect at 12:01AM PT on Tuesday, March 17th, and it will include San Francisco, Santa Clara, San Mateo, Marin, Contra Costa, and Alameda counties, according to the San Francisco Chronicle. The order, which will affect most businesses in the Bay Area, will stay in effect through April 7th.

San Francisco Mayor London Breed tweeted that the directive “will require people to stay home except for essential needs” and that “necessary government functions & essential stores will remain open.”

Effective at midnight, San Francisco will require people to stay home except for essential needs.



Necessary government functions & essential stores will remain open.



These steps are based on the advice of public health experts to slow the spread of #COVID19. — London Breed (@LondonBreed) March 16, 2020

The order bans nonessential gatherings of any size as well as nonessential travel “on foot, bicycle, scooter, automobile or public transit,” the Chronicle reports.

Travel for medical care, to shop for necessary supplies, and to help family and friends who need assistance will be allowed. Airports, public transit, and taxis will continue to operate for essential travel. People are encouraged to practice social distancing and keep six feet apart from others when possible. Delivery services that bring food, goods or services directly to residences can continue to operate as well.

“We are in a rough place, and we are going to have difficult times ahead of us,” San Mateo County Health Officer Scott Morrow told the Mercury News. “The measures we’re putting in place are temporary, but they will last longer than any of us want. This is the time to unite as a community, come to each other’s aid and dig really deep to find your best inner self and pull out all the compassion, gratitude and kindness you can.”

This is the biggest metro area in the US to implement such a lockdown in response to the outbreak. As of Monday morning, California had 335 confirmed cases of the virus, with 114 in the Bay Area and 37 in in San Francisco proper. In-person classes at Stanford University were canceled beginning March 9th after a faculty member tested positive for the novel coronavirus.

On March 11th, Breed ordered all gatherings of more than 1,000 people banned in the city for two weeks, but a few days later, the order was revised to ban gatherings of just 100 people or more. Nearby counties, like San Mateo, also recently began implementing social gathering bans of 50 or more people, which is what the Centers for Disease Control and Prevention now recommends.

Update March 16th, 5PM ET: Adds information that food delivery can continue and comment from San Mateo Health officer.