DETROIT -- Officials have shut down an international commuter tunnel connecting Detroit with Windsor, Ontario, as authorities investigate a bomb threat.
Detroit Windsor Tunnel chief executive Neal Belitsky says the tunnel was closed Thursday afternoon to traffic after the threat was called in on the Canadian 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. The bridge remained open on Thursday.
Associated Press