In S06E06, we here a gunshot...we also here a voice..."No..wait.."
What I could infer is: It is very unlikely that one of the suspects knew that in the next moment patrick is going to shoot and hence he yelled "No...wait..", because patrick had the gun pointed to them all the time...

Now, I could think of the following possibilities:

1. Patrick shoots something else other than suspects...which is weird and hence one of the suspects yelled ..."No ...wait.."

2. Definately, as we hear a gunshot which was from a shotgun....it was patrick that shoots and no one else...

Please comment if I am wrong..or if there is any other possibility...