Biden 'closely monitoring' situation at Rainbow Bridge as FBI investigates possible terror attack

President Joe Biden is 'closely monitoring' the suspected terrorist attack on Rainbow Bridge at Niagara Falls Wednesday. 

'The White House is closely monitoring the situation, law enforcement is on-scene and investigating,' a spokesperson for the National Security Council told DailyMail.com.

Biden is on Nantucket Island, off the coast of Massachusetts, with his family for the Thanksgiving holiday. 

A vehicle exploded at a checkpoint on the American side of a US-Canada bridge, prompting the closing of four border crossings in the area. Two occupants inside the vehicle were killed. 

The FBI Terrorism Task Force is investigating but officials are yet to confirm the motive. 

'This is obviously a very serious situation in Niagara Falls,' Canadian prime minister Justin Trudeau said in Parliament, as he excused himself from Question Period in the House of Commons to be briefed further. 

'We are taking this extraordinary seriously,' he added. 

The bridge connects U.S. and Canada. Three other bridges between western New York and Ontario were quickly closed as a precaution, and the Buffalo-Niagara International Airport began security checks on all cars and told passengers to expect additional screenings.