Question regarding police escort near Chicago on 6/3/17

Hello police men and women. Today on my way home from work, I was traveling South bound on I-294. At around 11:20 AM near Cicero Ave and 127th I saw a whole lot of Chicago police, a couple of State troopers, and an ambulance. They only had blue and white lights on and had the entire north bound side blocked off. I was wondering if you guys know what that was for. Thank you