The US Federal Bureau of Investigation (FBI) said on Wednesday it was looking into a vehicle explosion at the Rainbow Bridge border crossing between the United States and Canada, located near Niagara Falls.

The explosion took place near a security booth at the bridge’s US entrance.

Officials said two people were killed in the incident, according to US media reports.

New York governor confirms two dead, rules out terrorism motive

New York Governor Kathy Hochul confirmed the two fatalities in the blast at the checkpoint 400 miles (640 kilometers) northwest of New York City.

She 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."

The two victims' identities were not yet public.

Hochul said their vehicle may have been from western New York state.

US Senate Majority Leader Chuck Schumer said the FBI believes it has the identity of the driver involved in the incident.

Rainbow Bridge incident forces multiple border crossings to close

The Rainbow Bridge, which spans the Niagara River, remains closed Wednesday following the explosion.

Photos and video posted online by eyewitnesses showed thick smoke and flames near the vehicle as well as a damaged security booth.

One eyewitness told Reuters news agency that he had seen a vehicle speeding toward the bridge entrance before the explosion.

He said the vehicle had swerved to avoid colliding with another car then crashed into a nearby fence, "All of the sudden he went up in the air and then it was a ball of fire like 30 or 40 feet high."

Four border crossings in the Buffalo area, New York, have all been temporarily closed, and agents from the FBI's Buffalo Field Office are conducting an on-site investigation.

The Field Office also released a statement on X, calling the situation, "very fluid."

How had authorities responded?

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

Canadian Prime Minister Justin Trudeau excused himself as he cut short his Question Period in the House of Commons Wednesday, saying, "This is obviously a very serious situation in Niagara Falls," before he left for a security briefing.

Canada's Public Safety Ministry said it was taking the situation "very seriously," yet cautioned that it was too soon to say whether the incident was a deliberate act.

New York Governor Hochul said that all points of entry between Canada and New York were being monitored by the FBI's Terrorism Task Force.

Vehicles arriving at Buffalo Airport are also being subjected to security checks and people traveling for the Thanksgiving holiday were informed that they will be subject to enhanced airport security checks as well.

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.