SPARTA, Wis. - Wisconsin authorities say three young German women were killed when their rental car struck a deer and was then rear-ended by a tractor trailer.

The collision happened Sunday night on Interstate 90 near Sparta, which is in western Wisconsin between Milwaukee and Minneapolis. The Wisconsin State Patrol says the women slowed down after striking the deer and that the semi slammed into their car, pushing it into a ditch. The truck overturned.

State Patrol investigators say two of the women were 20 years old and the third was 22. It didn't release their names, hometowns or other details.

The semi's driver was treated at a hospital for injuries that didn't appear to be life-threatening.

Patrol Sgt. James Sawyer says autopsies are expected to be performed Tuesday in Madison.