California Gov. Gavin Newsom wants to limit where people can carry concealed guns. His Wednesday endorsement of legislation follows several high profile mass shootings left dozens dead across the state in January. The proposal would ban people from carrying concealed guns in churches, public libraries, private businesses and other places. The rule wouldn't apply if business owners post signage saying concealed guns are allowed. 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.