Why would the police know? We are not the FAA and we rarely get a heads up.
Just east of the track (near 16th St. and Tibbs Ave.) they were circling for about an hour in the dark this morning from approximately 05:30 to 06:30. This looked about like what I have seen in the past when the Police were searching for a suspect on the ground except this appeared to be two Blackhawks with no searchlights on.
PS: The last I heard IMPD had grounded it's helicopters due to a lack of funds and they were for sale.