STAMFORD - Stamford police say they're on the hunt for a 21-year-old man who started a large brawl at a barbecue.

Investigators say the suspect hit a woman on Chestnut Street Monday night while she was trying to break up an argument between two other men. 

Police say the incident sparked a large fight in which the man started punching people, including a 32-year-old man who was knocked unconscious and taken to the hospital with a serious brain injury.

Investigators say four women were arrested on the scene and charged with assault.

They expect to make more arrests soon.