Why was Buffy in the school?

[Joshua]

Why was Buffy in the school to save the boy from killing himself and his girlfriend in the beginning of "I Only Have Eyes for You"? Last I remember Buffy was at the Bronze.

 

[Chosen Enemy]

Giles was there too, I think. So maybe she came there from the Bronze for another training session, or to talk stragedy or something, like always. Even if we didn't see him in that scene, he could have been there. There were many times where Buffy and the Scoobies were on campus during night hours. Not so weird.