USA Canada Border Possible Terrorist Attack

The FBI is investigating a vehicle explosion that occurred Wednesday at the Rainbow Bridge border crossing between the U.S. and Canada.

The vehicle was heading from the U.S. to Canada and was going in the direction of the border officer building, sources told Fox News' Alexis McAdams.

All bridges were closed in the area, and all government buildings were evacuated, according to sources. Sources tell Fox News' Alexis McAdams that the incident was being treated as a possible attack.

Fox News' Alexis McAdams was told by sources that the explosion was so big and fierce, that authorities first thought it was a terrorist attack.