SACRAMENTO, Calif. — California Gov. Gavin Newsom has put the nation’s most populous state on a stay-at-home order.

It expands to nearly 40 million people restrictions he said already applied to about half the state. He said late Thursday that the statewide restriction on any non-essential movement outside the home is needed to control the spread of the coronavirus that threatens to overwhelm the state’s medical system.

Newsom earlier in the day issued the dire prediction that 56% of California’s population could contract the virus over the next eight weeks.