The siren was on for two seconds and it stopped. Please - ths was cold blooded murder.
Also what I noticed this time that it is very clear that the SWAT members were surprised by the man inside with the gun. You can clearly see them react with surprise when they started shooting.
That would not be the case if SWAT arrived to “cold blooded murder” this man, as you put it.
I recommend you watch the video again.