John Moody, 64, who retired as a driver in Pinellas County two weeks later, called the dispatcher about the July 9 fight and yelled at the 15-year-olds to stop the assault on a 13-year-old. Video of the incident was recently posted on the Internet.
"Me jumping in the middle of that fight with three boys, it would have been more dangerous for other students on the bus for as myself," he said. "There's just no telling what might have happened."
Prosecutors announced Thursday that Moody would not face criminal charges. The younger boy suffered a broken arm an two black eyes but Assistant States Attorney Bruce Bartlett said he got off the bus quickly once his attackers had left, giving Moody no chance to examine his injuries.
The video shows Moody yelled at the three assailants. He also made a desperate plea for help on the radio.
"You gotta get somebody here quick, quick, quick, quick," he told a dispatcher. "They're about to beat this boy to death over here. Please get somebody here quick. They're still doing it. There's nothing I can do."
The attack was apparently revenge because the younger boy had reported to school officials that one of the 15-year-olds had tried to sell him drugs.