Administrators initially banned all spectators from Saturday afternoon's varsity football game between Rich South and Rich Central after a brawl broke out late last month between students from the two schools. At least 16 teenagers were arrested.
The Southtown Star reports Superintendent Doris Langon initially limited fans because she was worried weapons would be brought to the game. But she relented, saying that keeping students, parents and fans away from the Olympia Fields game would have been unfair to players.
Access was limited to adult family members for Thursday's games between sophomore and freshman squads.
District officials say extra security will be on hand Saturday, and police will use metal-detecting wands as necessary.
Rich Township High School District 227's current evacuation plan calls for students to be bused from one school to another. Last Monday, students from Rich Central were bused to rival Rich South High School during a bomb scare.
The fire alarm was pulled once the other students arrived, and a massive brawl occurred between the students.
In the meantime, security has been upgraded at both schools.
The Associated Press contributed to this report.