Green Bay police responded to a one-car rollover crash in the 3800 block of East Mason Street near Finger Road just before 5 a.m. Saturday.
Officials believe the 25-year-old driver, who is now in custody, had been drinking.
A 23-year-old woman is in the hospital with life-threatening injuries. The driver and two other people in the vehicle sustained non life-threatening injuries.
A portion of Mason Street near the crash scene was closed off as the reconstruction team investigated the accident.