The Detroit-Windsor Tunnel has reopened after a closure prompted by the discovery of a suspicious package containing what authorities say is likely a smoke bomb or grenade.

Police in Windsor, Ontario, said in a statement that Canadian border agents were inspecting a vehicle with Michigan plates around 5 p.m. Tuesday when they found a bag containing a suspicious device.

Border officials closed the international crossing that runs under the Detroit River and notified Windsor police, who sent an explosives unit.

The statement says investigators believe the device is consistent with a smoke bomb or smoke grenade. Officers also found brass knuckles and knives inside the vehicle.

Police say the tunnel reopened just before 9:00 p.m.

The statement says the two men in the vehicle were taken into custody. An investigation is ongoing.