(CNN) — At least one person died in a car that exploded Wednesday at the US-Canada Rainbow Bridge border crossing, law enforcement sources told CNN.

The incident occurred shortly before noon in a car at the border on the bridge connecting Canada to New York State.

“This is obviously a very serious situation,“ Canadian Public Safety Minister Dominic LeBlanc told reporters Wednesday.

“We’re taking this circumstance very seriously but to speculate on the origin of this particular circumstance – the reasons why this may have happened – until we have more accurate information is simply not responsible.”

The explosion on the eve of the US Thanksgiving holiday has led to closures and delays on a busy travel day. All four bridges between Canada and the United States – including the Peace, Lewiston-Queenston and Whirlpool – were closed, officials said. Buffalo Niagara International Airport said travelers should expect additional screenings following the incident, and the US Federal Aviation Administration said the airport was closed to departing and arriving international flights.

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Four photos circulating on social media show the remains of a vehicle strewn about the US-side of the border crossing. CNN has geolocated and confirmed the authenticity of the four photos.

Thick smoke and fire can be seen in the photos. One image shows a border guard shack with significant damage and charred debris next to it.

Videos reviewed by authorities show the vehicle entering the bridge on the US side and then accelerating at a high rate of speed, according to multiple law enforcement sources familiar with the investigation. Earlier reports had indicated the car was traveling from Canada to the US.

The vehicle hit a curb and went airborne over a barrier, landing in a secondary search area, where it exploded, according to the sources.

Authorities are trying to determine if the individual the car is registered to is the driver found at the scene, but the condition of the remains has made it difficult for authorities to determine the identity of the driver, multiple sources told CNN.

It has also created a challenge for authorities in assessing if there were one or two people in the car. Law enforcement originally believed there were two individuals in the car, but they are now not certain.

The FBI, New York State Police and US Customs and Border Protection are on the scene investigating. Federal authorities are trying to retrieve video from a number of different angles because the statements from witnesses vary, sources said.

Sources said there were no other serious injuries reported.

The leaders of both the United States and Canada have been briefed and are closely monitoring the situation. New York Gov. Kathy Hochul said she is heading to Buffalo to meet with law enforcement and emergency responders.

Federal authorities in Buffalo, New York, said the “situation is very fluid.”

Earlier, the Niagara International Transportation Technology Coalition reported the bridge was closed on both sides due to a crash.

The bridge was reported closed at 11:51 a.m., according to the technology coalition. Camera footage from the coalition showed haze surrounding the bridge.

There are four ports of entry between Canada and the US near Niagara Falls, according to US Customs and Border Protection. All four were closed following the incident.

Every car coming into Buffalo International Airport is being screened with bomb-detecting dogs as the travel hub heightens security, a transportation official told CNN.

In the nation’s capital, the Metropolitan Police Department increased patrols on roadways and waterways as a precaution, a law enforcement official said. Officials said they are not aware of any credible threats.

This is a developing story and will be updated.

CORRECTION: A previous version of this story incorrectly described how the vehicle traveled through the border checkpoint.

CNN’s Laura Dolan and Kristina Sgueglia contributed to this report.