At about 30 minutes in the police audio an officer says the guy has not fired for about 15 minutes. I have not seen any reference to firing after that first ten to fifteen minutes.
Several of the 'early release' videos I saw were actually compilations from different cellphone cameras, etc. That made it difficult to tell whether the shots were continuous as none of the video segments had time-stamps.
The videos I saw has sporadic gun fire blasts, short delays, more blasts. It will take experts going through the various videos to determine a more exacting timeline. That is impossible to ascertain from the various cellphone videos.