DNR wardens say they still don’t know why…or how…an ATV crashed in Chippewa County this weekend.

That crash, which happened Saturday near Holcombe, killed a 6-year-old girl and her 16-year-old aunt.

A DNR warden says the agency is looking into everything in that fatal ATV crash…from speed to possible equipment malfunction.

"In a lot of ATV accidents, it's pretty obvious why the person went off the road or hit something or whatever,” Bill Yearman, with the DNR said. “Here, in this case, it's not. The evidence at the scene didn't point out exactly what happened."

Chippewa County Coroner, Kay Gerrits, says 6-year-old Elizabeth Winchel and the driver, 16-year-old Wendy Hattamer died from severe head injuries. Their ATV flipped and pinned them underneath.

Yearman says another 16-year-old girl was thrown from the ATV and is recovering from her injuries. He says the girls were not wearing helmets.

"Wisconsin law is anyone under 18 needs to be wearing a helmet when they're riding an ATV. And the reason for that is to help prevent or lessen head injuries."

Yearman says all three girls were riding on the same ATV. And while there’s no state law against that, he says it’s certainly not recommended.

"Let's say when you're riding on a trail. You have to shift your weight in order to turn the ATV. To turn sharply it's a weight shift,” Yearman said. “And obviously having 2 or in this case, 3 people trying to move their weights at the same time, in the same direction is extremely difficult at best."

Yearman says the ATV’s operator, Wendy Hattamer, had completed the appropriate ATV safety courses.

He says 13 people have been killed in ATV crashes statewide since January 1st.