SAN FRANCISCO, Calif. (KRON) — After San Francisco passed its ban on ghost guns earlier this year, city leaders gathered Wednesday to officially sign the ban into legislation.

Supervisors unanimously voted to ban “ghost gun” sales — which are weapons built from firearm parts sold without serial numbers, making them difficult to trace — on September 17.

Gun safety advocates, including Moms Demand Action volunteers, joined Supervisor Catherine Stefani and Mayor London Breed at the signing ceremony — which will now make it illegal to sell or distribute ghost guns in San Francisco.

San Francisco is reportedly the first city in the state to ban ghost guns sales.

“Ghost guns wreak havoc on our community and are far too easy to obtain,” said Supervisor Stefani in a tweet Wednesday.

“SFPD reports seizures of these unlicensed and unregistered firearms increased by more than 2,700% in San Francisco over the last four years.”

San Francisco Police reported it seized 164 ghost guns in 2020 — an increase from the six confiscated in 2016.

According to San Francisco District Attorney Chesa Boudin’s Office, California accounted for 65% of all ghost guns seized by the Bureau of Alcohol, Tobacco, Firearms and Explosives in 2020.