New York: The Rainbow Bridge crossing connecting the US and Canada near Niagara Falls has been shut as the federal authorities in Buffalo, New York, have said that an investigation is underway following a "vehicle explosion" at the crossing on Wednesday (local time), CNN reported.

Describing the situation as "very fluid", the Federal Bureau of Investigation (FBI) has said that they are in close coordination with local, state and federal law enforcement to carry out the ongoing investigation in the case.

"The FBI Buffalo Field Office is investigating a vehicle explosion at the Rainbow Bridge, a border crossing between the US and Canada in Niagara Falls," the FBI wrote on X.

"The FBI is coordinating with our local, state and federal law enforcement partners in this investigation. As this situation is very fluid, that's all we can say at this time," the statement said.

Citing the Niagara International Transportation Technology Coalition, CNN reported that the Rainbow Bridge crossing connecting the US and Canada near Niagara Falls has been shut down on both sides due to a crash.

A spokesperson for the mayor's office in Niagara Falls said that a vehicle was attempting to cross into the US.

The technology coalition stated that the collision caused the bridge to be closed at 11:51 am.

"We don't really know too much - just that there was a vehicle trying to come into the US and they shut down both sides of the bridge," public information officer for the city of Niagara Falls, Aaron Ferguson told CNN.

The technology coalition's camera footage revealed smoke encircling the bridge. US Customs and Border Protection lists four points of entry between Canada and the US close to Niagara Falls.

The investigation is underway. Further details awaited.