Austin Schoff, 18, was flown to South Bend after being hit by a car in the 10000-block of Michigan Road around 7:30 p.m. Friday.
The Marshall County Sheriff's Department reports Lauren Tanner, 17, was driving north on Michigan Road near 11th Road in a 2009 Suburban, when she suddenly saw Schoff wearing dark clothing walking near the edge of the road and hit him.
Tanner stopped her car a short distance away from the accident and called 911. Tanner's father, a Plymouth paramedic, was first on scene and called dispatch for Medflight immediately.
Medics rushed Schoff with head injuries to Plymouth Municipal Airport where he was transferred to a Medflight helicopter, which transported him to Memorial Hospital in South Bend.
Deputies said there is no reason to suspect drugs or alcohol were involved. The incident remains under investigation.