(CBS/AP)-- Traffic through an international commuter tunnel connecting Detroit with Windsor, Ontario, has been shut down as officials investigate a bomb threat.
A Department of Homeland Security official tells CBS News on background the threat was received on "the Canadian side." As a result, Canadian authorities shut down the Detroit-Windsor Tunnel.
U.S. Customs and Border Protection is investigating the threat from the U.S. side.
No further details were immediately available.
About 4.5 million cars used the 82-year-old underwater tunnel in 2011. It stretches about a mile beneath the Detroit River, between downtown Detroit and downtown Windsor.
It is one of two international border crossings in Detroit. The Ambassador Bridge is located just west of downtown.