Girl dragged by school bus in Louisville, Kentucky

New disturbing surveillance video shows a young girl being dragged by a school bus in Louisville, Kentucky, after her backpack got stuck in the door.

The incident happened on Friday. Police said the bus dragged the first grader about 100 feet. But neighbors described the distance as being at least a football field.

Witness Esther Karschner said she saw the girl's legs hanging out of the bus as it drove down the road, and a car sped alongside the bus, honking to try to stop it.

"I saw a car go flying by behind the bus real fast," Karschner said. "Shortly after the car stopped the bus. Her bookbag was caught on the bottom of the door when she got out."

The 7-year-old girl was hospitalized to be treated for road rash to her legs, Dwight Mitchell told ABC News.

Jefferson County school officials have launched an investigation.