Four border crossings in the area are closed. (Image: The Canadian Press)
Authorities say a vehicle has exploded at a checkpoint on the American side of a US-Canada bridge in Niagara Falls.
Four border crossings in the area are closed.
The FBI's field office in Buffalo is investigating the explosion on the Rainbow Bridge.
Photos and video taken by news organizations and posted on social media shows a security booth that had been singed by flames.