California Governor Gavin Newsom wants to limit the list of places where people can carry concealed weapons after numerous mass shootings that have left dozens dead, the AP reports.

To that end, he called for more restrictions in a state that has already passed some of the toughest gun laws in the United States.

On Wednesday, he approved a bill that would prohibit people from carrying concealed weapons into churches, public libraries, zoos, amusement parks, playgrounds, banks and all other private businesses open to the public. The rule would not apply if the owner of the establishment in question puts up a sign showing that concealed carry is allowed.

The bill also prohibits anyone under 21 from holding a concealed-carry permit, and all permit holders must receive additional training, including in the safe storage and transportation of guns.

Last year, the U.S. Supreme Court struck down a similar law, making it easier for residents of several states to obtain a concealed-carry permit.