The school released a statement on its website late Thursday, on the eve of the Trojans' semifinal game against top-seeded Arizona at Staples Center.
"We have received some information [Thursday night] about an incident involving coach Kevin O'Neill, his wife and a fan from another school that occurred following our men's basketball game today," USC athletic director Pat Haden said in the statement.
"We are looking into this and gathering facts. We will determine what appropriate action is necessary."
O'Neill, 54, is in his second season with USC and served as interim coach at Arizona for the 2007-08 season while Lute Olson took a leave of absence.
Diamond Leung covers college basketball for ESPN.com and can be reached at email@example.com.