The Niagara Gazette newspaper, citing law enforcement sources, said the car sped onto the bridge plaza, went through a fence separating the inbound lanes from the outbound lanes, and toward the inspection lanes, where it exploded.
CNN, citing unnamed sources, said the car was coming from the Canadian side toward the US.
The Rainbow Bridge and all three other border crossings along the Niagara River between western New York and southern Ontario – the Peace Bridge, the Lewiston-Queenston Bridge and the Whirlpool Bridge – were shut down indefinitely as a precaution, the New York governor’s office said.
Other international crossings remained open on “heightened alert status”, according to the governor.
The three bridges carrying road vehicles only across the Niagara River between Ontario and New York state are among the busiest border crossings in the world. The Whirlpool Bridge carries railroad traffic and vehicles.
Security measures were escalated at airports and railways in the region managed by the Niagara-Frontier Transit Authority, the governor’s office said.
Buffalo International Airport has closed to all departing and arriving international flights, the Federal Aviation Administration said on its website.
Security also was tightened at various locations around New York City, Mayor Eric Adams said in a statement.
“This is obviously a very serious situation. The government of Canada is taking this situation extremely seriously,” Public Safety Minister Dominic LeBlanc told reporters in Ottawa. “We are in close contact with American authorities. I will be speaking with the US Homeland Security secretary shortly,” LeBlanc said.
The explosion was under investigation by agents from the FBI field office in Buffalo, New York, the agency in a statement on the social media platform X, formerly known as Twitter.
“The FBI is coordinating with our local, state and federal law enforcement partners in this investigation,” the FBI statement said. “As this situation is very fluid, that’s all we can say at this time.”
Hochul issued a separate statement on X saying, New York state police, at her direction was “actively working with the FBI Joint Terrorism Task Force to monitor all points of entry to New York.”
Law enforcement teams in Canada also were “actively engaged in assessing the situation,” Ontario Premier Doug Ford said in a post on X.
Border agency officials in the United States had no immediate comment, while their Canadian counterparts did not immediately respond to a request for comment.
Representatives for the US State Department also did not immediately respond to a request for comment on the reported border closures.
The White House was closely monitoring the situation, as well, a spokesperson said.