Police say the vehicle involved in Tuesday's deadly train collision in Westbury may have been fleeing a prior car crash.

Around 7:20 p.m. Tuesday, authorities say three cars were lined up on the north side of the Long Island Rail Road grade crossing at School Street, waiting behind the lowered caution gates.

A witness tells police that an accident of some sort then took place. At that point, the middle car traveled southbound, evaded the gates, and traveled onto the tracks. That's when a train traveling eastbound packed with about 800 passengers smashed into the vehicle. The crash spun the vehicle into an oncoming westbound train. It was then sandwiched between the two trains and caught fire. The westbound train, which was carrying about 200 passengers, then crashed into the nearby Westbury LIRR station platform.

Police say they're still investigating whether the vehicle that was hit by the train was trying to escape a hit-and-run. All three people inside the vehicle were killed.

Officials say there would have been even more casualties if it weren't for the quick thinking of the engineer controlling the westbound train. Nassau County Police Commissioner Patrick Ryder says the engineer ran out of the front cab, pushing a passenger away from danger as well. Seconds later, the train took out about 350 feet worth of concrete platform. The front car was filled with concrete and metal.

MTA police are taking the lead in the investigation.

Authorities are yet to identify the people killed in the vehicle.