In a perfect world, this operation would have gone off without a hitch. Criminal activities would have restrained all the witnesses, kept them in check, Ananke and her team would have located all the infected without issue, and with a few well places bullets (and knives, and explosives if it really came down to it), every monster in the building would have been wiped out in the matter of an hour.
Of course, this world is far from perfect, and even the most carefully laid out plans can be derailed by none other than mass human stupidity.
Civilians are supposed to follow orders from military without question and without hesitation. Even without the training and discipline drilled into them, they're all aware of the law, and the consequences of breaking it. The unspoken rules were clear- you either obeyed, or suffered the consequences.
And yet, some of them decide not to obey. Some of them scream, some of them run, and some of them, bafflingly, resist arrest, as if being put in jail is worse than being eating alive by a living nightmare. It slows down the plan, prevents Ananke from locating the nearest infected as soon as she'd like, but it doesn't stop her from succeeding eventually. Herding in the humans is squad A-3's business. Her job is to kill every vampire in sight as quickly as possible.
Trapped in the pit serving as the area, the reaper is isolated, save for two victims that can already be written off as dead. It's easy enough for Ananke to localize her fire, and even though the reaper survives the first clip, the specialist can see it bleeding and slowing. Another round or two will put it down. This is good.
Then a stranger decides to grab her gun.
Ananke freezes.
She's unsure of what to do, mostly because no one has ever been so monumentally stupid enough to do this before. The possibility isn't even listed as a training scenario. “Are you crazy!?” The blond man snarls, as if he isn't the insane one for interfering with a military soldier's mission. “You could hit one of your own men!” He tries to convince her to stop, as if doing so won't mean risking exponentially more lives, military or not.
Not to say that friendly fire isn't a possibility, but Ananke and her team have trained to minimize the risk as much as possible. They've done countless drills, run countless scenarios, practicing and calculating and simulating dozens of formations to make each member as safe and effective as possible.
But explaining all this to this stranger, who is more an obstacle than a person at this point, would take too long.
"Let. Go," Ananke sees, jerking her weapon back in an attempt to free it. "You are obstructing official military business." It's a standard line, fed to her by protocol, but what she'd really like to say is 'or would you rather the Reaper eat us all first'.