Not everyone. Drake still is, but the rest are outside in the courtyard.
Also funfacts about Nurse Kaname
Fun Fact 1: She is a collector of poisons and venom's in her house (Which is on campus along with the other staff) she has over 100 different types of poison's and venom's in jars in her basement.
Fun Fact 2: Since she is basically undead and a creation of alchemy she can survive without her head. Her head can be detached from her body and she would still be alive. (her body would be limp, but her head would still be alive.) As long as her he isn't smashed or her heart isn't destroyed she would live. She has literally lost her head on more than one occasion while working at the University.