Police are investigating an accident Thursday night between a semi truck and a four-door passenger car on the southwest side that injured three men. The car was traveling south on South Harding Street near West Troy Avenue when it collided with the semi, which was northbound. Firefighters cut three male occupants from the car. Medics transported a 17-year-old to Methodist Hospital in stable condition, a second 17-year-old to Wishard Hospital in serious condition, and a 22-year-old to Wishard in critical condition. The semi driver was not injured.