My thoughts, pre-planning, walking through many scenarios , training / experiences in my life .......
You have a panic driven herd of kiddies stampeded down a brick and tile kill zone that an active shooter has planned aka hallway ...... my goal is to go to knee or on my side using a corner as cover and and try and shoot at an upward angle to miss the innocent and hit the guilty only , versus be ricochet rabbits bastard child that had to shoot the hostage per se to get to the evil liberal killer.
Plan A ....
God bless plan A, but you know what they say about plans and contact with the enemy.
Now truthfully, not having any idea what the engagement will look like, other than you're the only unknown adult in a sea of kids, do you think your chances of neutralizing an unknown target are better with a concealed pistol, or a rifle?