He said his son ended up with a leg injury and is going to be OK.
According to the Wisconsin State Patrol, the driver of the school bus pulled over onto the shoulder because of a mechanical issue.
The semi-truck then rear-ended the bus. Four of the students received serious injuries. None of the injuries were considered life-threatening.
This happened on the eve of a big day for the eighth-grade students, their graduation is scheduled for Thursday.
"I hope she's not all banged up," said Johnson.
The driver of the truck worked for Dahl Trucking. Ted Dahl, the owner of the company released a statement saying, "We're very sad that this happened. We pray for the families involved, and for the children to make quick recoveries."
The school also posted a statement on Facebook saying:
"While very scary, our staff and students were blessed by urgent first-responders, local medical attention as well as the kindness and generosity of Deforest Public Schools. Please keep our Semper scholars in your prayers for quick recovery and safe travels to reunite with loved ones."