FORT LEE, N.J. — A driver was shot in the head and killed in a suspected drive-by shooting on the George Washington Bridge Tuesday night, shutting down New Jersey-bound traffic for hours as police searched for the gunman.

Port Authority police responding to reports of a crash shortly after 7 p.m. found the man inside a car that had crashed on the westbound upper level of the bridge.

He had been shot in the head.

The driver was rushed to Englewood Hospital, where he was pronounced dead, according to law enforcement sources cited by the New York Post.

The suspected shooter fled and remained on the loose late Tuesday night.

Police were reviewing security camera footage from the bridge to identify the suspect and determine what led to the shooting.

Authorities have not released the victim's name or said what may have sparked the shooting.

No one else was injured.

The shooting shut down the entire New Jersey-bound upper level of the bridge, causing traffic backups stretching for miles.

As of 11 p.m. Tuesday, all westbound upper-level lanes remained closed, according to NJ.com.

Traffic heading into Manhattan was also delayed, although those lanes were later cleared.

Port Authority police and the NYPD responded to the scene.

The Port Authority confirmed that the driver was found with a gunshot wound after the crash but did not initially confirm his death. The New York Post reported that he died, citing law enforcement sources.

The investigation is ongoing.