WINDSOR, Ontario (AP) — The Ambassador Bridge border crossing between Canada and the U.S. was closed in both directions on Monday as authorities investigated possible explosives found in the area.

Windsor police said the area surrounding the bridge that links Windsor, Ontario, and Detroit has also been evacuated.

Police said traffic was being rerouted to the Windsor-Detroit Tunnel and the Blue Water Bridge.

Police said their explosives unit was on scene.

The bridge is critical to trade between the two countries.