In 2016, a Bucks County toddler accidentally killed himself when he picked up his father's loaded handgun and it discharged. In the months that followed, his father spoke to other parents about safety issues, as part of his sentence for involuntary manslaughter. Law enforcement officials started a gun lock distribution effort, which was named for 2-year-old Benjamin Smith.

And since April 2017, thousands of gun locks have been picked up at police stations, the sheriff's office, and community events, as well as distributed by social workers and given to concealed-carry permit applicants. Ring-shaped devices that prompt gun owners to unload and secure their firearms at home, the locks can prevent children or others who shouldn't have access to weapons from getting their hands on a gun.

"This is anecdotal, but we can't keep the gun locks in stock," said Bucks County District Attorney Matthew Weintraub. "Just the other day at the chiefs' meeting, I encouraged all of the chiefs, my law enforcement partners, to order 'em up, keep 'em coming."

Guns are in about one in three homes with kids, and an estimated 1.7 million American children live in a household with unlocked and loaded guns, according to research cited by the Children's Hospital of Pennsylvania. People who die from accidental shootings are more than three times as likely to have had a firearm in the home, and the majority of guns used in suicide attempts by young people are found in the home.

On average, one young person age 19 or younger is shot and killed unintentionally every day in the United States, according to the Brady Campaign to Prevent Gun Violence.

The Bucks County program has been so successful that the District Attorney's Office is hoping to expand it in 2019. Weintraub wants to distribute the locks to seniors, citing recent research about the risks of firearm ownership among people with dementia.

By 2050, 8 to 12 million people with dementia could be living in homes with guns, according to a study in the Annals of Internal Medicine. For both doctors and family members, talking to people with dementia about their guns can be difficult, and more than 100 people suffering from the disease shot themselves or others in recent years, a Kaiser Health News and PBS NewsHour investigation found.

"This is a natural audience to target for gun safety," Weintraub said.

The county's Network of Victim Assistance (NOVA), which works to prevent violence, has helped distribute gun locks. "The issue with elders who have dementia or early signs of dementia and may have guns in their home. … [Our] position is about the safety of those people and the people around them, and therefore we would … certainly support the district attorney in saying you need to lock up your guns" said Penny Ettinger, executive director.

The county's campaign is part of a national initiative by the National Shooting Sports Foundation called Project ChildSafe, which distributes the locks to law enforcement. Because many county police departments order locks separately, it's difficult to say exactly how many have been distributed in Bucks, but NOVA estimated that up to 10,000 gun locks have been picked up. NOVA itself has distributed about 4,000 to 5,000, said Angela McGettigan, director of resource development.

In Philadelphia, the Sheriff's Office started distributing gun locks in summer 2016, handing them out at community events and making them free to pick up at the office during business hours, and also says its program has been successful.

"Research tells us that a significant number of childhood gun accidents in the home can be prevented by using gun locks or trigger guards," said Philadelphia Sheriff Jewell Williams. "We're trying to develop a culture where gun owners are responsible and understand the need to secure their firearms at home."

Trigger locks have been criticized because the gun must be unloaded to be locked, meaning they don't prevent loaded guns from being fired. A law requiring trigger locks was struck down but the Supreme Court in 2008. The National Rifle Association has opposed mandatory gun storage laws, although safe storage techniques including trigger locks have been promoted on its website.

Bucks County has not had an accidental child death by firearm since Ben Smith's death, Weintraub said. His father, Nicholas Wyllie, was paroled in April, with three years of probation.

Use of a gun lock is intended to create a habit where a gun owner never leaves a loaded gun lying around.

"It is so simple to lock up our guns," McGettigan said. "Anyone can pick one up and place it on a firearm and protect the ones that they love."