Two Michigan men have been detained after a suspicious package found in their vehicle while entering Canada through the Detroit-Windsor Tunnel prompted the closure of the tunnel for more than three hours and evacuation of the border complex Tuesday evening.

The tunnel complex on the Canadian side was evacuated as a precaution while the Windsor police explosives disposal unit examined the package.

In a statement, Windsor police said the suspicious package was "consistent in structure as being a commercial grade smoke bomb or smoke grenade."

Smoke bombs can emit a thick cloud of smoke if ignited.

Police also seized a pair of brass knuckles, a switchblade and a butterfly knife.

Tunnel reopened

The tunnel reopened by 8:45 p.m. ET, according to the Canada Border Services Agency.

The tunnel bus is also running again after Transit Windsor suspended service.

Police said a vehicle with Michigan licence plates driven by the men entered Canada via the tunnel around 5 p.m.

The two men were sent for secondary inspection and a suspicious package was found in a bag inside the vehicle.

When a vehicle arrives at a land border crossing, the driver must speak to an agent. Should further investigation of the driver or vehicle be required, they are sent to secondary inspection at a larger office, located just beyond the booth.

The tunnel, which connects downtown Windsor with Detroit, can handle as many as 2,000 cars an hour.

wdr_border traffic

Traffic backs up along the Ambassador Bridge heading into Detroit, while the Detroit-Windsor Tunnel was blocked in both directions. (