GOOSE CREEK, S.C. —  A highway was shut down outside Charleston after police found a "suspicious item" in a car during a traffic stop, authorities said Sunday.

Charleston County Sheriff Al Cannon would not say what the item was, but said that a bomb squad planned to demolish it.

Cannon said two men who were in the car were still at the scene at 2 a.m. An FBI agent said officials were trying to determine whether a crime had been committed.

Julie Johnson, assistant special agent-in-charge for the FBI in Columbia, said there was "no immediate threat," The (Charleston) Post and Courier reported late Saturday.

Law enforcement officials closed the road about 7 p.m. after the traffic stop in Goose Creek, home to the Naval Weapons Station. The station houses the U.S. Naval Consolidated Brig, a military prison where enemy combatants have been held.

The traffic stop took place about 7 miles from the sprawling Navy facility.

Johnson said the FBI was still trying to determine whether a crime had been committed but that there was "no immediate threat" related to the traffic stop.

Goose Creek, with a population of about 30,000, is located about 20 miles north of Charleston.