A border crossing between the U.S. and Canada has been closed after a vehicle exploded at a checkpoint on a bridge near Niagara Falls, according to the Niagara International Transportation Technology Coalition.

The FBI’s field office in Buffalo said in a statement that it is investigating the explosion on the Rainbow Bridge, which connects the two countries across the Niagara River.

“The FBI is coordinating with our local, state and federal law enforcement partners in this investigation,” a statement posted on X reads. “As this situation is very fluid, that’s all we can say at the time.”

The Department of Justice said Attorney General Merrick Garland has been briefed on the explosion. The White House is closely monitoring the situation, law enforcement is on-scene and investigating, according to a National Security Council spokesperson who spoke on condition of anonymity because of the sensitive nature of the situation.