Four people were dragged under the vehicle.
Slater Mayor John Kahler said he was told that bystanders picked the car up off of those who were trapped under the car.
“This just happened to be an unfortunate accident where some elderly people seemed to be leaving the situation quickly and lost control of their vehicle,” Kahler said.
Mary Nienow, 59, of Alberta Lea, was killed.
A 67-year-old woman, a 30-year-old woman and a 6-year-old child were also injured.
Each year, 5,000-6,000 people descend on the town of about 1,500 residents for its Fourth of July festivities.