Ughh. I know how you feel. It's a horrible situation. I honestly don't know what I would do.
I know this is dumb for me to put this on the internet... but I go to the university that recently had the professor(Amy Bishop) shoot other professors during a faulty meeting (I'm guessing you might have heard of this, it was on the national news in February) Classes were canceled for a week after that since it was such a tragedy, and quite frankly, nobody felt safe enough.
Ever since then you don't know who to trust. Before you only thought you had to worry about other students, but now, professors? Staff? UGH!
The other day in class, we heard someone run down the hallway screaming, we all got really scared... but turned out it was someone's kid misbehaving.. -phew-
A lot of the time, when someone makes a threat its for attention so officials don't do anything about it. But you really can't assume that nothing will happen.. But you can't cancel school every time someone makes a threat either..
With all that is going on in the world, classes should be canceled tomorrow while they investigate it further. If enough parents complain to the superintendent then they would have to cancel, but since it is late at night on a Sunday I doubt that could happen in time.
Keep us updated on whatever you decide to do and whatever happens.