Updated

A prosecutor says criminal charges are possible after reports that a Long Island Rail Road engineer let a passenger operate a train bound for New York City.

Nassau County District Attorney Kathleen Rice says her office is investigating what could have turned into a "mass casualty situation."

A witness told railroad police that he saw a passenger in the cab without the engineer during part of a run on July 2.

MTA police say the train ran smoothly and no one was injured.

The LIRR calls the allegations "extremely serious and troubling." The Federal Railroad Administration also has been notified.

The engineer has been suspended without pay.