Authorities say they have a pretty good idea why it happened. They're saying a slick highway combined with just driving too fast caused seven cars to crash into each other shortly after six Monday night.
The Mosinee Fire Department says a car was heading south on I-39, just south of highway 34, and lost control. At the same time, a car traveling north did the same thing. Two cars went in the ditch, but were able to get out.
Rescue teams from Mosinee, Wausau, Rothschild and Knowlton responded. Four or five people were hurt, according to the Mosinee Fire Department.
Captain Gary Colbert says it's not extremely surprising this happened.
"When you get snow-covered roads, and you get multiple vehicles traveling on that time of day, you're gonna have slippery conditions, and that's exactly what happened."
He says you're best off to just take it easy on days like this.