What does this dream mean?

i had a dream about a teacher with a gun and there were alligators attacking us. the teacher killed everyone in the school except for me and my closest sister. the gun was a big basooka thingy. then the teacher was trying to kill me and my sister but we wound up killing her in the end and everyone else came back to life. in real life this teacher is a kindergarten teacher and she is really nice. can someone tell me what this dream means?