State police say a crash critically injured a trooper on the off-ramp from the Long Island Expressway to the Sagtikos Parkway Monday afternoon.

Police say State Trooper Joseph J. Gallagher pulled over on the ramp around 2:30 p.m. to help a pair of disabled motorists. He was placing road flares when another driver struck him.

Paramedics from the Suffolk County Police Department's Medical Crisis Action Team arrived within a minute, according to Maj. David Candelaria, of the state police. 

"They rendered advanced life support," he said, and likely saved the trooper's life.

He was taken by ambulance to Southside Hospital in Bay Shore in critical condition, and he underwent surgery. Following the surgery, he was listed in serious condition.

Police say the driver remained at the scene and no charges have been filed in the crash.

Gallagher is 35 years old and has been on the job for three years. He previously served in troops F and T before coming to Long Island's Troop L at the beginning of this year.

State police are asking any witnesses to the crash to contact SP Farmingdale at (631) 756-3300.