An investigation by the Greater Harrison Drug and Violent Crime Task Force led officers to pull over a vehicle Thursday afternoon in Clarksburg.
During the stop, officers seized a gun, heroin and cash, officials said.
The officers pulled a black Nissan Juke over near the intersection of Marshall and East Pike streets, just off the Joyce Street exit of U.S. Route 50 around 3:30 p.m.
Eight or more uniformed and plainclothes officers, some of them wearing masks, bulletproof vests or carrying rifles were on the scene.
This was part of an ongoing investigation, according to an ATF agent on the scene.
No arrests related to the incident have been announced yet.