Nearly 7 million people have been ordered to “shelter in place” around the Bay Area of northern California.

Six Bay Area counties announced its “shelter in place” order Monday for all residents, directing them to practice social distancing by staying home for the next three weeks in an effort for public health officials to combat the spread of the coronavirus.The order, which goes into effect 12:01 a.m. Tuesday, affects more than 6.7 million in San Francisco, Santa Clara, San Mateo, Marin, Contra Costa and Alameda counties. It is effective until at least April 7 and is the most restrictive yet in the country.

Although the order isn’t a full lockdown, it’s unclear how it will be enforced, but calls for the sheriff or chief of police to “ensure compliance.”

“The scientific evidence shows that at this stage of the (coronavirus) emergency, it is essential to slow virus transmission as much as possible to protect the most vulnerable and to prevent the health care system from being overwhelmed,” the order states. “One proven way to slow the transmission is to limit interactions among people to the greatest extent practicable.”

The order bans non-essential gatherings of any size as well as non-essential travel “on foot, bicycle, scooter, automobile or public transit.” However, residents may travel to get necessary supplies, access health care and provide aid to family and friends in need of assistance. While public transit remains operation for only essential travel, people are expected to keep six feet apart.

The order also advises elderly people and those with underlying health problems to stay inside except for when they need to acquire health care.

Regarding “routine medical appointments” and elective procedures, the order urges residents to either cancel, reschedule or do appointments remotely if possible.

The order directs residents to work from home or to stop working, unless they provide an essential service such as health care.