Funeral services were scheduled this week for the three Girl Scouts and one of their mothers who were killed Saturday in Wisconsin by a driver allegedly under the influence of chemical vapors.

Sara Schneider, 32, and her 10-year-old daughter, Haylee Hickle, will be memorialized at a service Thursday at the Chippewa Valley Bible Church in Chippewa Falls. Jayna Kelly, 9, will be eulogized at the same church the following day.

A funeral service will also be held Thursday for 10-year-old Autumn Helgeson at Our Saviour's Lutheran Church in Chippewa Falls.

The four were killed Saturday while participating in a Girl Scouts highway cleanup project.

This photo provided by the Chippewa County Sheriff's Office in Wisconsin shows Colten Treu, who is accused of striking and killing three Girl Scouts and a parent and critically injuring a fourth girl who were picking up trash along a rural roadway near Chippewa Falls last weekend..  (Chippewa County (Wis.) Sheriff's Office via AP)

According to police, Colten Treu, 21, struck five members of the group after his pickup truck veered out of its lane, crossed the highway's center line and ended up in the ditch. He had allegedly been inhaling chemical vapors to get high prior to the crash.

The surviving girl was hospitalized in Rochester in critical condition.

Treu left the scene but later turned himself into Lake Hallie Police about five hours after the crash. He has been charged with vehicular homicide.

Fox News’ Travis Fedschun and The Associated Press contributed to this report.