New York: Two people were killed in a "vehicle explosion" at the US-Canada border crossing near Niagara Falls in the afternoon hours on Wednesday, CBS News reported citing sources.

Four US-Canada border crossings in the region have been closed as investigators respond to the situation, it said.

Two people were killed inside the vehicle that exploded, according to several law enforcement officials who verified the information to CBS News. The nationalities of the two people who died are not yet known, officials said.

A senior US law enforcement official told CBS News that the car was coming from the US side. It hit the customs station and the vehicle was charred. It is not yet known why the car exploded.

A senior administration official described the incident to CBS News as "more than a freak accident, but we don't yet have details."

A Canadian visitor to New York, Mike Guenther, said he was walking close by when the incident happened and he noticed the vehicle speeding in the direction of the border crossing.

"And he was flying, over 100 miles an hour. There was a car in front of him, he swerved out, went in front of the car, hit the fence, went flying up into the air ... and we saw the fireball, and that's all we could see, there was just smoke everywhere," he said, according to CBS News.

Meanwhile, the FBI Buffalo Field Office in a statement posted on social media platform X, said, "The FBI Buffalo Field Office is investigating a vehicle explosion at the Rainbow Bridge, a border crossing between the US and Canada in Niagara Falls. The FBI is coordinating with our local, state and federal law enforcement partners in this investigation. As this situation is very fluid, that's all we can say at this time."

The Rainbow Bridge, which links Niagara Falls, Ontario, Canada, and Niagara Falls, New York, is a well-liked tourist destination. The Lewiston-Queenston Bridge, the Whirlpool Rapids Bridge, and the Peace Bridge are the other border crossings in the area.

Following the incident, New York Governor Kathy Hochul has said in a statement "At my direction, the New York State Police is actively working with the FBI Joint Terrorism Task Force to monitor all points of entry to New York."

Adding further, she stated that as of now, she is on her way to Buffalo to "meet with law enforcement and emergency responders," and take stock of the situation.

The Rainbow Bridge crossing connecting the US and Canada near Niagara Falls has been shut as the federal authorities in Buffalo, New York, have said that an investigation is underway.