Owen Sound police say one man was taken to hospital after an early morning fight downtown.
Police say it started when a group of youths got into an argument with another group of youths.
According to police, man was walking by in the area and decided to intervene.
A fight ensued between him and one of the youths, when the youth's friend arrived with a baseball bat.
Police say the man was hit with the bat temporarily knocking him unconscious.
Police and paramedics responded and the man was transported to the hospital for serious but non life threatening injuries.
Officers arrested the youth, and he now has a court date for assault with a weapon, assault causing bodily harm and for having a Weapon for a dangerous purpose.
Because of his age, the accused cannot be named.