Authorities have identified the registered owner of the vehicle involved in the incident on the Rainbow Bridge, law enforcement sources tell CNN.
The car came from the US side and was traveling toward Canada, according to a law enforcement source and another source briefed on the investigation.
Law enforcement officials have conducted a video canvass of the surrounding area in the hours since the incident occurred and found the car appears to have been at a nearby New York casino before the incident. This is one reason officials are urging caution in labeling the explosion as an attempted terrorist attack, the law enforcement source said.
The FBI is working to identify the bodies of the dead occupant or occupants in the car and see if there's any evidence of explosives, both sources said.
Authorities are trying to determine whether the car is registered to the driver 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.