Ok I don’t remember much but to me it was a scary movie because I was so young.  I believe there was a man locked away in some kind of maze like facility/it might have been located underground. I think some kids snuck or were brought to the facility for whatever reason. (one of their parents worked there??) The power went out and somehow he got out, started killing all the people he would eat their brains I belive it helped him get stronger.  The survivors killed him and found their way out I think it looked like they came out from an entrance in the mountains.  This is all fuzzy to me as it has been so long.