The incident happened in the parking lot at Millburn High School in New Jersey around 2:30 p.m. Friday.
"The person assaulted was simply an innocent victim coming to the aid of another student," superintendent Richard Brodow told the Star-Ledger. "I believe he intervened to protect someone."
Police arrested 58-year-old Rverend Darryl George, 19-year-old Lamar George and a 15-year-old juvenile who is a student at the high school. Lamar George is a graduate. Brodow says the current student has been suspended.
School board president Samuel Levy told the newspaper that the father and older son came to school at dismissal time to confront a student who had had an "exchange of words" with the younger son.
"Another student came to his defense, and that kid was subsequently beaten," Levy told the paper. "The younger son also assisted in some way."
Authorities say the injured student, an 18-year-old senior, was treated for bruises.
Darryl George is charged with possession of a weapon for an unlawful purpose, unlawful possession of a weapon, conspiracy, aggravated assault, endangering the welfare of children and use of a minor in a criminal offense.
Lamar George is charged with possession of a weapon for an unlawful purpose, unlawful possession of a weapon, aggravated assault, conspiracy, terroristic threats and use of a minor in a criminal offense.
The court set bail for both adults at $10,000.
WEB PRODUCED BY: Bill King