NIAGARA FALLS, Nov 23 — A car erupted into a fireball at a US-Canada checkpoint near Niagara Falls yesterday, killing the two occupants, triggering border closures and sparking a massive security alert on the eve of a major holiday.

New York Governor Kathy Hochul confirmed the two fatalities in the blast at the checkpoint 640 kilometres northwest of New York City and said nothing pointed to a "terrorist” attack.

"There is no evidence at this time that this was terrorist activity,” Hochul told a briefing. "(It was) a horrific incident, a crash, an explosion... but at this time no known terrorist connection.”

While the two victims’ identities were not yet public, she suggested their vehicle may have been from western New York state.

Witnesses described seeing a car traveling at high speed before it crashed into a checkpoint barrier and exploded into flames.

The explosion happened at the major Rainbow Bridge crossing near Niagara Falls with nothing left of the vehicle which Hochul said was incinerated except for the engine.

Authorities on both sides of the border activated emergency responses and images showed access roads to the crossing swarming with emergency service workers and vehicles.

The White House said President Joe Biden had been briefed and was closely following developments.

Canadian Prime Minister Justin Trudeau told parliament "this is obviously a very serious situation.”

‘He was flying’

"We’ve seen this car coming down towards the border and he was flying — over 100 miles an hour,” Mike Guenther, a Canadian visiting the United States, told CBS News.

The car then swerved and "hit the fence, went flying up into the air,” he said. "He went up into the air and we just seen the fireball and that’s all we could see. It was just covered in smoke everywhere.”

The incident came on the eve of the Thanksgiving holiday, one of the busiest days for travel when millions of Americans take to the roads and skies.

Rainbow Bridge — among the busiest crossings between Canada and the United States — has 16 vehicle lanes and is normally open around the clock, according to US Customs and Border Protection.

Hochul said that debris was spread across as many as 14 of the lanes following the incident.

Three other nearby border crossings had been closed in the aftermath of the incident, but had since reopened, US Customs and Border Protection said.

On the US side, Niagara Falls State Park, which attracts millions of visitors every year, was closed until further notice according to the parks service.

Canada’s Public Safety Minister Dominic LeBlanc said "any time... (infrastructure like) a border crossing sees this kind of violent circumstance, it’s a source of concern for” US and Canadian authorities.

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.

Multiple witnesses reported hearing a loud explosion and seeing a large cloud of smoke near the inspection station.

Fire, black smoke

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.”

New York City Mayor Eric Adams said that officers of the city’s police department, the country’s largest, had deployed to the border crossing to assist the investigation.

"The city’s partners have already enhanced security, and the city is on heightened alert due to the upcoming holiday,” he said.

Dramatic videos showed thick plumes of black smoke rising from a conflagration at the crossing. — AFP