Alright today I was passing through DFW about to exit the North Entrance, and an American Eagle ERJ-145 passed over the airplane overpass. Pretty Normal, as you see almost everything going over to the Terminal A C E side of the airport. Suddenly I noticed there were 2 police cars (Looked to be Dallas, not DFW police) with lights flashing quickly chasing the airplane. Seconds later it stopped, but I had to keep going and did not find out what happened. Any Info?