DETROIT (AP) -- The tunnel linking Detroit and Canada will close on Sunday so police can hold drills.
According to MLive.com (http://bit.ly/1rpvwnP ), the Detroit-Windsor tunnel will be shut down for three hours in the morning.
The Detroit Department of Homeland Security calls it an "annual tunnel exercise."
Thousands of vehicles cross between Detroit and Windsor via the tunnel each day.
The next two nearest Canadian border crossings are the Ambassador Bridge in Detroit and the Blue Water Bridge in Port Huron.