MADISON, Wis. (AP) - Detectives investigating an assault that left star Wisconsin running back Montee Ball with a concussion have identified "several persons of interest" and believe the altercation may be related to a fight five days earlier, Madison police said Saturday.

Investigators determined that a fight occurred late on July 27 and into the morning of July 28 involving Wisconsin students, members of the football team and others, according to a police statement. Ball was present but there is no indication he participated in the fight, police said.

One person was injured during that fight and was treated at a hospital.

Five days later, five men roughed up Ball near campus. Ball was walking down a street Wednesday around 2:15 a.m. after "socializing" with friends, police said. Two friends walking ahead of him turned around and saw Ball on the ground. The men had surrounded him and were kicking him in the head and chest.