NIAGARA FALLS, New York: A vehicle speeding toward a US-Canada bridge from the American side crashed and exploded at a checkpoint in Niagara Falls on Wednesday, killing two people and prompting the closing of multiple border crossings for hours. Authorities weren't sure what spurred the wreck but said there were no signs it was a terror attack.

The FBI's Buffalo office said late Wednesday that it had concluded its investigation: 'A search of the scene revealed no explosive materials, and no terrorism nexus was identified,' it said in a statement. 'The matter has been turned over to the Niagara Falls Police Department as a traffic investigation.'