Witnesses describe vehicle explosion at U.S.-Canada border: "I never saw anything like it"

Witnesses at a U.S.-Canada border crossing described the chaotic high-speed crash that led to a vehicle explosion at Rainbow Bridge on Wednesday.

The collision at Rainbow Bridge, a U.S.-Canada border crossing near Niagara Falls, in western New York, left two people inside the vehicle dead, multiple law enforcement sources confirmed to CBS News. 

Mike Guenther, a Canadian visiting the United States, said he saw the vehicle speeding toward the crossing from the U.S. side of the border when it swerved to avoid another car, crashed into a fence and exploded.