the SWAT team had been activated on higher alert already 6-7 minutes before the first shots were fired…
given that they were standing next to the tents and did not want to draw too much attention to their presence to keep the general public under control, it would make sense that they sent out one of them to go have a look.
in the bodycam footage it is clear that immediately after the 1st shot he positioned himself, took aim by the 3rd shot and fired immediately after the burst of 5 went off, so his response time was about 4 seconds…
I think such a response time is fairly quick when starting from walking around to hitting the man on the roof and/or his rifle…
and then, about 7-9 seconds later he looks through his scope to assess the damage, and here, I think he shot the 10th round to finish the man off.
I do not think the 10th shot came from any of the barn snipers as the damage to the body would have been considerably worse if he had been hit with a sniper rifle round (typically a .300 winchester magnum), and they were using suppressed rifles, and that round would likely have been subsonic…
this may seem many assumptions in 1 sentence, but it is clear they had suppressors on their sniper rifles and I believe that snipers 1 and 2 (the ones that had their line of sight hindered by the tree) returned fire almost immediately after the first round came in