2 Dead In US-Canada Border Crossing Blast: Report

US-Canada border crossings near Niagara Falls were closed Wednesday as terrorism investigators responded to a vehicle explosion at Rainbow Bridge, local and state authorities said.

Two people were killed in the blast, according to US media citing authorities. Their identities were not yet clear.

The cause of the incident was not immediately clear but New York Governor Kathy Hochul said state police and the FBI Joint Terrorism Task Force were monitoring all points of entry into the state.

US media cited law enforcement sources as saying there were two people in the car, which had passed through one border checkpoint where it was selected for a secondary check.

The car then sped up, crashed into a barrier and exploded, the sources said, stressing it was unclear if the blast was the result of a device.

"I am traveling to Buffalo to meet with law enforcement and emergency responders and will update New Yorkers when more information becomes available," Hochul posted on social media.

Canadian Prime Minister Justin Trudeau's office said he had been briefed and was in contact with US law enforcement. Multiple Canadian agencies were supporting the investigation, it added.

Witnesses reported hearing a deafening explosion and seeing a large cloud of smoke near the inspections station.

Ivan Vitalii, a visitor from Ukraine, told the Niagara Gazette he and a friend were at a nearby convenience store on the US side when they saw a car exit a parking lot and travel toward the bridge.

"We heard something smash," he said. "We saw fire and big, black smoke."

Ron Rienas, of the Buffalo and Fort Erie Public Bridge Authority, told ABC News all four bridges connecting the two countries over the Niagara River have been closed.

Dramatic images posted to social media, which AFP has not verified, purported to show thick plumes of black smoke rising from a large conflagration at the crossing.

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)