U.S. border officials have released a video of the moment before a vehicle exploded Wednesday at the Rainbow Bridge, showing a speeding car going airborne and crashing into a booth.

The stunning video was posted on the social media account of the U.S. Customs and Border Protection (CBP) hours after the incident that left two people in the car dead and one border officer with minor injuries.

At the top of the footage, a few metres away from border booths, a white car is seen travelling at a high rate of speed. The vehicle then hits a median, sending it flying into the air. The car flips mid-air before crashing down.

The car and the booth then exploded and burst into flames, New York Governor Kathy Hochul said at a news conference late Wednesday afternoon, calling the video "absolutely surreal."

"You actually had to look at and say, was this generated by AI because it was so surreal to see how high in the air this vehicle went. And then the crash and explosion and the fire," Hochul said.

"When you see this video, your jaw will drop in disbelief at how this went so high – over an eight-foot high fence. It's rather extraordinary," she added.

Another video captured the aftermath of the incident, showing a burning vehicle at the crossing. Huge plumes of black smoke can be seen billowing out of the car.

"I've never seen anything like this. The car just exploded," the person who shot the video can be heard saying.

Hochul said she had been briefed by U.S. law enforcement that, based on the evidence they have at this time, there is no sign of terrorist activity in connection with the incident.

"You don't know whether the intent of the driver was intentional in how they drove. We do not know that," Hochul said when asked what could have caused the incident. It is also unclear where the vehicle originated.

She noted that one of the individuals in the car was from Western New York, but could not provide further details on their identities.

In a statement released Wednesday evening, the Federal Bureau of Investigation said it had concluded its probe at the scene and found no explosive materials. The FBI added that "no terrorism nexus was identified."

"The matter has been turned over to the Niagara Falls Police Department as a traffic investigation," the agency said.

The Rainbow Bridge remained closed Wednesday evening as an investigation into the incident got underway. The three other border crossings reopened late this afternoon.

Hochul said the investigation could take days.

“This is a large, widely scattered scene and we're trying to identify all the elements to make sure that there is no unforeseen situations that we need to address before we can open again to the public,” the governor said.

“We're going to make sure the public is safe before they go back on the Rainbow Bridge.”