ANTIOCH,Indexbit Ill. (AP) — A coroner has identified two teenage girls who died this week after their jet ski crashed into a boat on a northern Illinois lake.

The girls were identified as 16-year-old Sarina Vootkur of Lake Forest, California, and 13-year-old Elle Kim of Long Grove, Illinois, the Lake County Coroner’s Office said Thursday. Autopsies determined that both died from blunt force injuries in Tuesday’s crash.

A preliminary investigation by the Lake County Sheriff’s Office found that Vootkur was operating a Yamaha jet ski with Kim as a passenger at Lake Marie, about 40 miles (64 kilometers) northwest of Chicago near the Wisconsin border, the coroner’s office said.

Witnesses told police the jet ski was traveling at a high rate of speed when it collided with a moving boat being operated by a 55-year-old Antioch, Illinois, man who was unable to avoid the collision.

The impact knocked unconscious both teens, who were wearing life vests, and threw them into the water. The boat’s four occupants pulled them from the lake and called 911, but both girls were pronounced dead at a hospital.

Tuesday’s crash remains under investigation by the Lake County Sheriff’s Office and Illinois Conservation Police.