DETROIT, Mich.– For the second time in four days, traffic between Canada and the US was snarled at Detroit-Windsor due to a bogus bomb threat.

Last night around 7:20, a call to authorities on the US side of the Ambassador Bridge which claimed a bomb would go off in 10 minutes forced the closure of the bridge to all traffic. The bridge was not reopened till 1 a.m. once security sweeps were conducted and did not find a bomb.

Police roadblocks were set up near the bridge and  canine units were called in to search the bridge. The Coast Guard was on duty patrolling the Detroit River beneath the bridge and blocked river traffic until about 1 a.m. Tuesday as well.

More than 100 trucks were caught in the bridge closure but the traffic mayhem spread beyond the bridge to expressways and other major roads leading into downtown Detroit.

Car and light truck traffic was diverted to the Detroit Windsor Tunnel about 2 miles away, however large trucks cannot use the underwater commuter tunnel.

The bomb threat came just four days after a similar threat, this one called in to Windsor authorities, forced a four-hour shut down of the Detroit Windsor Tunnel, which connects Detroit and Windsor beneath the river.  Again, no explosives were found.

Meanwhile, the president of the Detroit International Bridge Company told media he suspects Monday’s bomb threat against the Ambassador Bridge is somehow related to cuts to the Canada Border Services Agency.

“We cannot confirm, but suspect that this is has something to do with Canada’s disinvestment at the border by cutting back on customs agents,” president Dan Stamper wrote in a statement to media. “The Detroit International Bridge Company remains vigilant in its efforts to ensure that all those who cross the Ambassador Bridge remain safe.”

Jason McMichael, first national vice president of the Customs and Immigration Union, quickly shot back that Stamper’s comment is “mindless rhetoric” and “so perverse, it’s laughable.”

“Despite the fact they are faced with cuts and despite the fact they have been working without a contract for the last year, these folks go to work every day and protect the Canadian economy, Canadians and international travellers,” McMichael said of his union’s members.