A speeding car crashed in flames on the bridge linking New York state and Ontario at Niagara Falls on Wednesday, killing two people in the vehicle and sparking a security scare that closed four U.S.-Canadian border crossings.

Hours later, federal and state authorities said investigators had found no evidence of an act of terrorism, though circumstances surrounding the crash on the Rainbow Bridge remained murky, leaving it to be determined whether it was accidental or intentional.

“At this time, there is no indication of a terrorist attack” or threat to the public, New York Governor Kathy Hochul told reporters on Wednesday evening. Her comments were echoed by federal and local law enforcement officials at a separate news conference.

The FBI said in a statement it had concluded its investigation. “A search of the scene revealed no explosive materials, and no terrorism nexus was identified,” the FBI said in a post on X, formerly known as Twitter.

Video of the crash caught on security camera and posted to X by the U.S. Customs and Border Protection (CBP) agency showed the car traveling from the U.S. side at high speed, then hitting an object and flying into the air before crashing to the ground and exploding in flames.

The driver and a passenger perished in the wreck, and a CBP officer suffered minor injuries. He was treated at a hospital and released, an agency official said later.

Authorities did not identify the two people killed. CNN reported the driver was a 56-year-old man who was traveling in a Bentley automobile with his wife to attend a concert by the rock group KISS.

A performance of the band scheduled for Wednesday in Toronto as part of the group’s farewell tour was canceled after one of its members, Paul Stanley, came down with flu.

The U.S. Federal Aviation Administration (FAA) said on its website the Buffalo Niagara International Airport had closed, but Hochul said there were no interruptions.

‘Heightened alert’

The crash unfolded at a time of heightened security concerns around the world stemming from the conflict in the Middle East and at the peak of U.S. holiday travel on the eve of Thanksgiving celebrations.

The Rainbow Bridge and all three other border crossings along the Niagara River between western New York and the Canadian province of Ontario - the Peace Bridge, the Lewiston-Queenston Bridge and the Whirlpool Bridge - were shut for several hours as a precaution.

Other international crossings remained open on “heightened alert status,” the governor said.

Security measures were escalated at other airports and railways managed by the Niagara-Frontier Transit Authority, as well as at various locations around New York City, officials said.

The three bridges that were not involved were reopened early Wednesday evening, but the Rainbow crossing remained closed during the investigation and as officials assessed the crossing’s safety.

Hochul said the car that crashed sailed over an 8-foot-tall fence before landing in a fireball that incinerated the vehicle, leaving little but the engine visibly intact and scattering debris over more than a dozen security booths on the bridge.

Witness Mike Guenther told Buffalo television station WGRZ-TV that he was walking near the bridge with his wife when the car, traveling at high speed, struck a fence at the crossing and was catapulted into the air before exploding.

“He was flying, over 100 miles an hour,” said Guenther, who was visiting from Kitchener, Ontario. He said the vehicle, which he described as a luxury sedan, was “fish-tailing” out of control before it crashed.

“It was a ball of fire, 30 or 40 feet high, never seen anything like it,” said Guenther.