Six Bay Area counties — San Francisco, Santa Clara, San Mateo, Marin, Contra Costa and Alameda — announced a “shelter in place” order. The lockdown, unveiled at a press conference earlier, starts at 12:01 AM Tuesday. It’s not a full lockdown, but it’s quite sweeping and strict nonetheless, as Northern California attempts to curb the exponential spread of COVID-19.

“There is no need to panic,” San Francisco Mayor London Breed said in a press conference today, continuing a plea for cooler heads amid the pandemic.

The order will be in place through April 7. Breed added that the date could be adjusted, based on how things play out. “It could be amended to be lengthened or shortened,” she explained, “depending on advice from our public health members.” The team aims to prioritize three elements during the crisis: reducing community spread through social distancing, protecting vulnerable populations and protecting healthcare workers and first responders.

Per the SF Chronicle, the included communities total more than 6.7 million people. The move follows previous city and state-wide bans on gatherings of more than 250 people, but takes a far more aggressive approach, banning travel via “foot, bicycle, scooter, automobile or public transit” that is deemed non-essential.

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

Exclusions include healthcare, purchasing “essential” supplies and aiding friends and family who require support. There’s also an exception for non-Bay Area residents looking to return home. Both airports and public transit will remain open under limited operation for essential travel, while requiring people to maintain a six-foot “social distancing.”

Services like police, fire and garbage pickup will remain throughout the lockdown. Police Chief Bill Scott noted that the police department isn’t looking to enforce the rules, but appeared to apply that it is willing to do so, if needed. There will also be an exception for “operation of the government agencies and provide for the health, safety and welfare of the public.”

Grocery stores, banks, pharmacies and gas stations will remain open to help residents pick up essential supplies. Breed added that “there is no need to rush out and do these things.” Bars and gyms will shut down, however, while restaurants will only be open for takeout. Food delivery will be active, as well.

An exemption will also be provided for the large homeless population that resides in the Bay Area, though the city is recommending they seek lodging at a local shelter. Last week San Francisco announced a plan to deploy RVs across the city to quarantine homeless residents infected by the virus.