Chesterton police said officers responded to a report of someone who had suffered a possible head injury and was lying in a roadway in the Tamarack subdivision at 10 p.m. Wednesday.
Officers said the 18-year-old Chesterton High School student fell from a moving vehicle near Laurel Creek Drive and Catkin Circle and was transported from the scene for medical treatment. Their condition was not immediately known.
Police described the "senior assassin" game as "an informal, tag-style game, often organized by high school seniors near the end of the school year," adding that "participants attempt to 'eliminate' one another using water guns or similar harmless devices, frequently tracking each other outside of school hours."
Police said the student organizer of the CHS Senior Assassin game has since agreed to cancel this year's event due to safety concerns.
Police are investigating and asked anyone with information to contact Cpl. Arwen LaMotte at 219-926-1136 or at alamotte@chestertonin.org.