Officials say 35-year-old Joseph Gallagher was critically injured after stopping to help a motorist on the Long Island Expressway.

A New York State trooper is fighting for his life after being struck by a vehicle on the Long Island Expressway.

Officials say 35-year-old trooper, Joseph Gallagher stopped to help a motorist, who broke down near an exit ramp on Monday afternoon when he was hit. Gallagher was taken to the hospital with a head injury and is listed in critical condition. Gallagher is originally from West Seneca, NY.

Investigators say the person who hit Gallagher remained on the scene and is cooperating with authorities. So far the driver has not been charged.