According to the Wisconsin State Journal, Central District Captain Carl Gloede says the police are trying to find out "what the incident was, when and where it happened."
The police are also looking into whether or not Ball or any other Wisconsin football players were involved.
Gloede also said that a witness told the police that one of Ball's assailants said something like "one down, nine to go" suggesting that there are other targets.
As for the TMZ report that Ball was involved in a fight at a player's home before the attack, and that Ball emphatically denied, the police said the incident TMZ reported is "not what we're looking at."
Ball suffered a concussion and had to be treated at a local hospital following the attack. He will miss the start of Wisconsin training camp on Monday due to the concussion.
The Heisman finalist finished the 2011 season with 1,923 rushing yards and 39 total touchdowns for the Badgers.