Fatal Explosion on Rainbow Bridge: Two Dead in Attempted Terror Attack from Canada to US

 An attempted terror attack on Rainbow Bridge at Niagara Falls today saw a car explode, causing a massive explosion at a toll checkpoint that killed the vehicle's two occupants.

Fox News cites law enforcement sources who say the intention was a larger attack to kill more an the FBI Terrorism Task Force is investigating but officials are yet to confirm the motive.

It remains unclear if anyone aside from those in the car were injured.

The City of Niagara Falls says the explosion came from a car that was trying to enter the US from Canada. It comes just two days after an intelligence report signaled increased risk of a terror attack in New York City.

After the explosion, motorists who'd driven into America were told to leave their vehicles and walk back into Canada while the cars were checked for bombs.

The aftermath of the explosion at Rainbow Bridge border crossing at Niagara Falls on Wednesday after a suspected terror attack

Witnesses who were in the US Customs and Immigration building next to the bridge were turned away, ordered to walk back over the bridge and leave their vehicles on the US side to be checked. '

'There was an explosion just by the tall building you go in. My own van was parked so close to the car that exploded, if you watch the video, the car was right on the left hand side.

'When the explosion happened, we heard it like a loud boom. I heard it but I didn't think it was something serious. Someone said "oh my god, the car exploded.'

'We all went to watch. Then the US border and custom officials came out of their glass room and then I grabbed my phone, said I need to film this before they start moving us away from here. The smoke got thicker, and thicker and thicker. We're there then US Customs come out and said all of us we need to move this way.

'They moved us to a safe passage,' said one man, whose truck was parked 'next' the burning vehicle.

The FBI Terrorism Task Force is investigating. 

                       The explosion left the vehicle in pieces next to the toll checkpoint in

The explosion was reported on Wednesday afternoon. It's unclear if there are any fatalities or injuries, and the origin of it remains unknown

 '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 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 bureau said.

A tourist visiting Canada who at the scene told DailyMail.com she could see plumes of smoke rise into the air and were told they wouldn't be able to cross.

Photos she took shortly after the event saw white smoke rising from the scene.

She was attempting to cross over into the US for a walk from Canada when they were turned around.

She said: 'It must have just happened as we'd come up to it. Moments before the guard had said as long as we have passports, it's fine.

'Then we were told not go over and to try again in a couple of hours.'