A US father has been arrested after he allegedly tried to run over a group of teens he believed had bullied his daughter.

Roy Williams Jnr, 56, reportedly confronted the youngsters with a cane after his 13-year-old daughter got in a fight outside Nelson Elementary School in Rockford, Illinois.

Williams then jumped into his 4WD and allegedly tried to run the group over.

Video of the frightening incident, which has since gone viral, was taken by Nathan Velez, who says the unhinged attack was indiscriminate.

"He was just going after everybody," the teenager told WREX.

"We came over to see what was going on," Nathan's mate, Trey Telfair said.

"We heard there was a fight and the next thing we know her dad showed up.

"People saw it, so they started running."

According to Nathan, Williams' daughter "got into a little fight with this other girl and hit her."

"He came around this way where everyone was running to and he went down that way and reversed and that's when he drove onto the grass," he said.

"He was coming at us and he was revving his engine to speed up when he was getting close to people and when he got close to me I just jumped out of the way," Trey added.