Downtown Black Diamond was the site of an early-Monday raid that uncovered drugs and assault weapons at a home near Lawson Street and Botts Drive.
During the bust, police arrested two men and two women.
“A month ago we started the investigation off a tip,” said Black Diamond Police Commander Greg Goral.
Goral said city officers were able to confirm through the investigation residents of the house were selling methamphetamine and marijuana.
As part of the investigation, Goral said, officers discovered a convicted felon was selling assault rifles. The man offered to sell an AK-47 assault rifle and sold an SKS assault rifle. The man also offered to sell an Uzi assault weapon.
Police obtained two search warrants, one for the house and one for a trailer near the house.
Multiple agencies were involved in the bust including the Washington State Patrol SWAT (special weapons and tactics) team and the Coalition of Small Police Agencies Special Operations.
The one male and two females have been charged with trafficking methamphetamine.
The fourth man was charged with being a felon in possession of a firearm.
Also found in the house were about 20 marijuana plants.
The investigation of the home continues.
Goral said the case has been the lead item for the Black Diamond Police Department for the past month.
