SAN MATEO, Calif. (KRON) – Four people have been arrested for trafficking firearms from Arizona to California, according to the San Mateo County Sheriff’s Office.

On Jan. 20, multiple arrest and search warrants were executed throughout San Mateo County and at a residence in Oakland.

Photo: San Mateo County Sheriff’s Office

Following this operation, authorities seized 15 firearms, thousands of rounds of ammunition, a suppressor attachment, automatic pistols, high-capacity magazines, and a 3-D printer.

During the investigation, a total of 30 firearms were recovered and four suspects were arrested — Two of them were taken into Federal Custody.

In Oct. 2021, a joint operation began between the San Mateo County Sheriff’s Office, the Bureau of Alcohol, Tobacco, Firearms, and Explosives, the San Francisco Police Department, and the San Francisco Drug Enforcement Administration Metro Task Force.

Authorities were able to identify and target suspects trafficking firearms from Arizona to California. The guns were being illegally sold throughout San Mateo County.

Undercover agents purchased multiple firearms during the investigation — These firearms included Ghost Guns, serialized firearms, high-capacity magazines, armor-piercing ammunition, and automatic rifles.

The sheriff’s department is “committed to preventing gun violence in our communities and would like to thank investigators from STF, SFDEA Metro, and the SFPD for their continuous support.”

As the investigation continues, you are asked to contact authorities if you have any information.