Kirsten's single family house has two different house numbers on it. On the left 986 to the right 984 This can be seen during the morning scene after Kirsten leaves the house in the middle of the night.
When the odd music "triggers" Kirsten, Kirsten snatches Damon's sidearm and holds everyone at gunpoint. Damon's sidearm is a Glock, and the trigger is in the rearward position, meaning that the gun is not cocked and thus cannot be fired. Damon would have known that, since it was his own gun, and therefore he would have known that he could have simply charged and tackled Kirsten with no risk of being shot.