TOWN OF MADISON, Wis. (AP) - Police say a fatal shooting at a Madison-area bar stemmed from an argument between two groups of people that escalated into a physical confrontation between one man in each group.

An update Sunday from the Town of Madison Police Department says investigators are still trying to determine why it happened. Police Chief Scott Gregory asked potential witnesses to come forward so investigators don't have to track them down.

Gregory says a 41-year-old Dane County man was killed in the clash at Pitcher's Pub early Saturday, while a 23-year-old Dane County man was injured. He ran away after the first shot was fired. Four more shots were heard as he was running. He was wounded in the head and was taken to a hospital for treatment.

Names have not been released.