Gee...you would think yahoo would include such pertinent information in their article...
My bet is the principal had already called the police the second she was buzzed in...
Being pro-active knowing she was unhinged...
The school called the mother in the first place and buzzed her in.
If they thought she was unhinged and a danger, they would not have buzzed her in.
The whole *point* of a buzzed in system is that you have the option of *not* buzzing someone in if the evidence suggests that someone means to harm others.