Researchers looked at firearm fatalities in the 13 years immediately after the Supreme Court limited local governments’ ability to restrict gun ownership.

Firearm deaths of children and teenagers rose significantly in states that enacted more permissive gun laws after the Supreme Court in 2010 limited local governments’ ability to restrict gun ownership, a new study has found.

In states that maintained stricter laws, firearm deaths were stable after the ruling, the researchers reported, and in some, they even declined.

Guns are the leading cause of death in the United States for people ages 1 through 17, according to the Centers for Disease Control and Prevention. Dr. Jeremy Faust, an emergency room doctor at Massachusetts General Brigham Hospital in Boston, who was the study’s lead author, said he was dismayed to find that most of the children’s deaths were homicides and suicides.

“It’s surprising how few of these are accidents,” Dr. Faust said. “I always thought that a lot of pediatric mortality from guns is that somebody got into the wrong place, and I still think safe storage is important, but it’s mostly homicides and suicides.”

John Commerford, executive director of the NRA Institute for Legislative Action, called the study “political propaganda masquerading as scientific research.”

The study, published Monday in JAMA Pediatrics, examined the 13-year period after the June 2010 Supreme Court ruling that the Second Amendment, which protects the right to bear arms, applies to state and local gun-control laws. The decision effectively limited the ability of state and local governments to regulate firearms.