The 33-year-old, who is on the card of UFC 149 in Calgary on July 21, was driving when he saw a group of teenagers attacking two others near MacLeod Trail.
"They were assaulting them," Ring said. "One of the attacker girls was kneeing the victim girl in the face.
"They beat the tar out of them. These poor kids had cuts all over their face from the strikes they'd taken."
Ring says when he jumped out of his car, he was joined by another bystander. After checking on the victims, he and the bystander gave chase and caught one male.
Ring followed the others while he called the police.
"They had no idea who I was," Ring said. "They were running away like scared little rats. The cops caught up with them.
"As as I was pointing them out, one of them challenged me to a one-on-one match. He said that he would take me."
A Calgary Police Service spokesperson said the victims were a male and female, both 17. One was treated for minor injuries.
"Their faces were bloody and cut open," Ring said. "It was a really sad thing to see. They didn't deserve what they got. They were outnumbered. I had to even out the playing field."
Ring believed the female attacker stole the female victim's backpack, but police said a backpack wasn't involved and called the incident "an altercation."
A 16-year-old male, a 17-year-old male and a 15-year-old female, who were among the group accosting the victims, have been charged with assault.
Ring's career record is 12-1, including 2-1 in UFC.