The San Mateo Sheriff's office announced Thursday that 30 illegal firearms were seized and four people were arrested after a three-month investigation conducted with the Bureau of Alcohol, Tobacco, Firearms, and Explosives, the San Francisco Police Department and the San Francisco Drug Enforcement Administration Metro Task Force.
The investigation uncovered the trafficking and sales of firearms brought in from Arizona, according to the Sheriff's office.
Undercover agents purchased firearms, including privately made firearms (commonly referenced as ghost guns), serialized firearms, high-capacity magazines, armor-piercing ammunition and automatic rifles.
On Thursday searches were conducted throughout San Mateo County and in Oakland. Investigators seized multiple guns, thousands of rounds of ammunition, a suppressor attachment, automatic pistols, high-capacity magazines and a 3D printer, a technology often used to make illegal guns.
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