Fairfield police say they found a suspicious box that tested positive for radiation during a traffic stop on Kings Highway Friday afternoon.

Officers made the traffic stop at around 1 p.m. when they saw a car pass by with misused plates. They say the three people inside the vehicle seemed suspicious, and they subsequently shut down the roadway until the fire department and state police could arrive on the scene.

Authorities say they found a soil density testing machine inside the box. They said one of the people inside the vehicle worked for a company that tests soil.

Police say the machine should not have been transported in the trunk of a regular vehicle.

Nearby employees had to evacuate for about two hours.

Kings Highway has since reopened. The vehicle involved in the incident was towed.