Video footage posted on social media purported to show the moment the car exploded and the fireball that resulted.
Photos from the scene showed strewn wreckage around one of the security stations on the American side of the bridge.
Neither US or Canadian authorities have yet announced any kind of explanation for the incident, names of those involved, or potential motive if it was an attack. However, Canadian Prime Minister Justin Trudeau said officials were “taking this extraordinarily seriously,” and the US FBI field office in nearby Buffalo, New York, was investigating the situation.
The White House also said US President Joe Biden had been briefed and was closely monitoring the situation.
New York Governor Kathy Hochul has confirmed that “there is no indication of a terrorist attack."
According to eyewitnesses who spoke with US media, the car accelerated after passing a security checkpoint on the US side of the bridge, swerved to miss other cars, and was launched airborne after striking a concrete barrier. It reportedly exploded upon impact with a concrete pillar holding up the pavilion over the second security checkpoint.
US law enforcement officials said no explosives had been detected among the wreckage so far.
The incident has resulted in the closing of all four border crossings along the Niagara River, which connects Lake Erie and Lake Ontario.