Platteville police said they called in a bomb squad after discovering suspicious packages during a traffic stop early Sunday morning.
Police said they stopped a vehicle for speeding at about 12:47 a.m. outside of the Platteville Police Department at 165 N. Forest St.
Police said the vehicle's owner, Joseph A. Baliff, 23, of Lancaster, was a passenger in the vehicle, and he displayed a firearm in a threatening manner.
The vehicle's occupants were detained to facilitate further investigation, the Platteville Police Department said in a news release.
During a search of the vehicle, police said they found two suspicious devices.
Authorities established a perimeter around the vehicle and called the Dane County Sheriff's Department's Explosive Ordinance Disposal Unit to the scene.
The Explosive Ordinance Disposal Unit rendered both devices safe, police said.
Police said the incident remains under investigation and it will be referred to the Grant County District Attorney's Office for consideration of applicable charges against Baliff.