The term "Police Scanner" can sometimes be insufficient. Most police scanner apps actually pick up a wide spectrum of police, fire, commercial and ham radio feeds.
Emergency Radio is no different.
You'll gain access to thousands of live feeds including EMS, air traffic, NOAA and more. The list of available feeds is always growing, and you can search and save your favorites. You'll even be able to listen in the background while running other apps.
Note: Not every city in the states has feeds available in this app. Check the list on the home page (linked below) to see if your city is included before you shell out $1.