A man was arrested for stabbing a 17-year-old boy at Smith Point Beach Saturday night in Shirley.

Authorities say 18-year-old Alexander Murphy, of Sayreville, stabbed the victim in the back with a knife during an altercation.

Witnesses said a helicopter arrived shortly after the attack to rush the teen to the hospital.

"Probably he was fighting with someone, but the police came...and they then pulled him back to the ground because the guy was trying to run," said Angel Guzman, an eyewitness.

Police say the teen is being treated for serious, but non-life-threatening injuries.

Murphy has been charged with assault and criminal possession of a weapon.

He is set to face a judge once he is released from the hospital.