This wasn’t some random shooter. It was an officer (or whatever capitol security). Look at any video of a police shooting-no one runs away screaming their head off. They stand in disbelief or they back out of the way/do as they’re told because when a police officer has their gun drawn, people are aware that the officer is likely pointing it at a specific person(s) doing a specific activity. You don’t worry about the police officer shooting everything that moves, just the person(s) in their line of sight.

For the record, people do back out of the way once the shot is fired. Because it’s a police officer and it’s understood you’ll only be shot if you try to climb through the window as Babbitt had just done, you likely don’t have to worry about getting shot. After the dust settled, people started coming back by Babbitt to help/stare at her while she’s dying.