California Gov. Gavin Newsom wants to limit where people can carry concealed guns after multiple mass shootings left dozens dead across the state in January, calling for more restrictions in a state that already has some of the nation’s toughest gun laws.

He endorsed legislation Wednesday that would ban people from carrying concealed guns into churches, public libraries, zoos, amusement parks, playgrounds, banks and all other privately owned businesses that are open to the public. The rule wouldn’t apply if the business owner puts up a sign that says concealed guns are allowed.

Democratic state Sen. Anthony Portantino, the bill’s author, called that exception “a legal nuance that I think helps it with constitutional muster.”

“This is not window dressing. This is to put a strong bill on the governor’s desk to withstand a legal challenge that is sure to come,” Portantino said.

It would also ban anyone younger than 21 from having a permit to carry their gun concealed and would require all permit holders to have more training, including on how to safely store and transport guns.

California and half a dozen other states previously had laws that required people to give a reason if they wanted to carry a concealed gun in public — like citing a direct threat to their public safety.

But a U.S. Supreme Court ruling last year struck down those laws, making it easier for people in those states to get a permit to carry a concealed weapon.

California Democrats tried to pass new rules last year — and they would have succeeded, had it not been for a strategic blunder requiring a two-thirds vote of the Legislature so the bill could take effect immediately. Democrats could not round up enough support, and the bill died.

“That’s not going to happen this year,” Newsom said. “I will be signing this legislation.”

Newsom and legislative Democrats vowed to double down on passing a new law this year. Their cause came with renewed urgency, after mass shootings in Monterey Park and Half Moon Bay left 18 people dead and 10 others wounded. In total, the state had six mass shootings in January and at least 29 people were killed.

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