Newsom said the state has been conducting pandemic planning for a decade, using artificial intelligence and modeling. Planning projections show as many as 56% of people in the state could become infected by the novel coronavirus over a period of about eight weeks, if steps to mitigate the spread — like tonight’s order — are not taken.

Newsom said, with the hospitalization rate predicted by some models, the state would need an additional 19,543 hospital beds over and above current capacity. That need could be reduced, he said, by changing behavior.

“If we meet this moment, we can truly bend the curve to reduce the need to surge, to reduce the need to have to go out and cobble all those assets together,” the governor said. “Though I want you to know we are doing just that.”

This shelter-in-place order mirrors what's happening in the Bay Area and elsewhere. Californians can go out for essential errands such as medical appointments, grocery shopping or to do critical jobs, but are otherwise advised to stay away from others.

“You can still take your kids outside, practicing common sense and social distancing. You can still walk your dog,” Newsom said of the state order.

Essental services such as gas stations, pharmacies, grocery stores, banks and laundromats can remain open. Dine-in restaurants, bars and nightclubs, entertainment venues and gyms are specifically mentioned as prohibited from opening.

Newsom's executive order also defines workplace exceptions to the order as those included on the U.S. Department of Homeland Security's list of "critical infrastructure sectors," which would include a wide variety of jobs, from communications to finance to food and agriculture.

The governor said intense efforts are being made to arrange for more hospital beds and ventilators, and he said that Seton Medical Center in Daly City has been secured to provide around 700 more beds. He said the state will acquire access to a Southern California hospital in the coming days.

He said the state is also continuing to work to find motel rooms for people who are homeless, and added that officials are in talks with the University of California and California State University systems to reserve dormitory space for future virus patients.

Newsom said the state received the first national stockpile transfer of assets, which included hundreds of thousands of gloves and protective masks. Those items, along with protective gear from the state's own supplies, is being distributed to communities throughout California, he said.

The governor said he knows the new shelter-in-place order is disruptive to families, especially to families with children.

“Check in on loved ones; check in on your neighbors,” Newsom said. He said the state will be announcing partnerships to aid residents, including with the neighborhood online site Nextdoor.com He added, “This is not a permanent state. This is a moment in time, and we will meet this moment together.”

Jon Brooks contributed to this post.