Windsor police are investigating after a suspicious package was found at the Windsor-Detroit Tunnel on Tuesday evening.

Police were called around 5 p.m. after a vehicle entering Canada was sent to secondary inspection by the Canadian Border Services Agency (CBSA).

Officials say a bag in the Michigan-plated vehicle contained a suspicious device prompting the CBSA to close the tunnel and evacuate staff.

The Explosives Disposal Unit (EDU) was called in and used a robot to inspect the pakage and found an unmarked cylinder with a fuse consistent with a commercial-grade smoke bomb or smoke grenade.

A smoke bomb emits a thick cloud of smoke when ignited. The device was taken into the custody of the EDU to be made safe.

Windsor police Sgt. Matt D'Asti says, "There is no reason at this point to be concerned about safety."

Two Michigan residents in the vehicle were detained in connection with the incident and face weapons charges.

Windsor police say the men were in possession of brass knuckles, which is a prohibited weapon in Canada, as well as a switchblade and butterfly knife.

The tunnel was re-opened to traffic around 9 p.m. once the area was deemed to be secure.

The investigation continues.