The Stair Case

In a city where most construction is done in the rain, a new 20-story high-rise foundation had to have tons of water dumped on it to cure it. The city passes a new building code early and the contractor must add two more subfloor staircases to both sides of the foundation.
The FBI is conducting a SWAT exercise in the same high-rise building many years later. They move the civilians to an upper floor after the building has been opened for a time. One old fellow is missed in the shuffle and goes to the very bottom #3S floor. They halted the elevators during the exercise. Coming up to the main lobby by the staircase, he finds it is full of terrorists. He tries to hide down stairs.
What could cause the exercise to go deadly and have the FBI Commander order his second unit into the building with live ammo?
Why was the radio tech for the exercise, which is a mousy looking, purple colored hair, female with glasses, be field promoted to a Special Agent by the FBI Commander? The Commander next tells his second in command to shoot any agent that does not do what the newest Special Agent says.
Why does the medical staff start to look at the knives the dead SWAT members are still carrying?