Quite a few things happened in the span of a few seconds.
Firstly there was Frazz who had attempted to push through the hallway full of armed men, unsurprisingly it was unsuccessful and he was shoved back away from the formation as everyone is very tense right now from the possibility of actually dying right here right now and never seeing their families ever again, so they're not taking any bullshit from anyone.
Then the door to the dissection room is kicked in by Aria, that knocked aside an Intern girl, can't possibly be older than 24, Dazing her as she suddenly find herself struck in the face by a door then her back slams into the wall next to said door. Aria carries the momentum and rolls into the room and smoothly up into a kneeling position with her Gauss rifle raised and leveled on the monster, at this range, compared to what you've been shooting at extreme range before, it's a piece of cake to try and go for it's skull.
Next comes in Virgil a fraction of a second later, he grabs the nearest Intern, which happens to be the stunned lady, and throw her into the hallway. There's still at least 10 more fleeing into the general direction of the door and it's going to clog it up real bad real soon..
A couple of Security and Rookies made it through, with the Security already having their grenades armed with a push of the button, out of the two, one of them managed to throw a HE at 001B.
.. The grenade landed a few feet away from where he had been aiming and rolled a little further, the creature is still well within it's blast range.
The second security, however, did not manage to throw his grenade as he locked up in fear from seeing such a terrifying monstrous creature, 001B decided to reaction fire at the man holding a beeping thing in his hand, it's Spike pierced halfway through him, blood and gore exploded out from his back through his useless security vest and it's momentum carries him to the nearby wall behind him, pinning him to it, killing the security immediately. He didn't even manage to cry when his whole body goes limp, his hand dropping the armed grenade and it rolled towards the door..
Then Maximus manage to make it through the door, his auto shotgun beginning to swing for 001B as he spots the rolling grenade.
..5..