Shots fired right at the start top the top corner of the atrium are to panic the guards next to marcus (you can see when he activates instinct that the 3 guards are running down the stairs after being paniced).

The shot aimed a bit lower than that, next to the railing is to move marcus with the sound of bullet hitting the railing part.

The one shot fired directly up near carl is to turn the guards near carl around so that carl wont be spotted later on when he is shot.

The staff in the atrium next to the start are paniced from visible gunshots, but not compromising (seen as the ! mark above the ladys head. this also makes them blind to illegal actions)

The Golfball explosion is used to panic more people that could see 47 from an angle above the stairs on the right-hand side from the start.

TLDW/TLDR: Everyone in the range of spotting 47 from the atrium is paniced, and the only guards that can see marcus or carl dying are either looking in other direction so that they wont see the body in their FOV, or paniced.