Gov. Mary Fallin of Oklahoma vetoed a bill on Friday that would have eliminated the need for training and permits to carry a gun in public, dealing a blow to gun-rights activists in one of the most firearm-friendly states.

The bill, which had broad support in the state’s Republican-controlled Legislature but had troubled some law enforcement officials, “would have eliminated the requirement to complete a short firearms safety and training course from a certified instructor and demonstrate competency with a pistol before carrying a gun in public,” according to the governor’s office.

“I believe the firearms laws we currently have in place are effective, appropriate and minimal, and serve to reassure our citizens that people who are carrying handguns in this state are qualified to do so,” Ms. Fallin, a Republican, said in a statement.

As do most states, Oklahoma currently requires adults to have a license to carry a handgun, whether openly or concealed. The bill, which was written by State Senator Nathan Dahm, would have created a much simpler route to legally carrying a gun in public: turning 21 years old.