A driver who fatally struck three Girl Scouts and a mother along a Wisconsin highway was “huffing” chemicals prior to the deadly crash, police said.

Colten Treu, 21, turned himself in to police hours after the crash in Lake Hallie that also sent another girl to the hospital, the Eau Claire Leader-Telegram reports.

Police identified the victims as Jayna S. Kelley, 9, and Autum A. Helgeson, 10, both of Lake Hallie, as well as Haylee J. Hickle, 10, and her 32-year-old mother, Sara Jo Schneider, both of Lafayette. They were picking up trash along the highway when they were cut down.

Another girl who was not immediately identified remained hospitalized Monday in stable condition, according to the newspaper.

Treu’s truck was found abandoned in Chippewa Falls after an officer tracked leaking fluid nearly two miles from the crash scene. A passenger in Treu’s truck also surrendered to police in Eau Claire, but that suspect had not been identified, the newspaper reported.

Treu was scheduled to appear in court in Chippewa County Court on Monday. He’s expected to face 13 possible charges, including four counts of homicide by intoxicated use of a vehicle, sheriff officials told the Star Tribune.

Police and witnesses said Treu was speeding on a highway when his truck veered into a shallow ditch where the girls and Schneider were picking up trash as part of an “Adopt-A-Highway” group.

The group of seven girls and five parents had “highly visible” green safety vests on at the time, police said in a statement.

Treu and his unidentified passenger both admitted to “huffing” chemicals prior to the crash, police said. Treu has a previous conviction for drunken driving in 2014, according to the Star Tribune.

The killed girls were students at the Halmstad and Southview elementary schools in Chippewa County, where grief counselors were on hand as classes resumed Monday.

“Our hearts are with our Girl Scout sisters in Chippewa Falls, Wisconsin,” Girl Scouts CEO Sylvia Acevedo tweeted on Sunday. “No words can ease the pain of a tragedy of this magnitude. Girl Scouts everywhere stand with you during this difficult time.”