aka Death School, aka School Night Massacre
How bad is it? It might be the worst Swedish film I've seen.
Should you see it? No.
Kids break into their school to solve a mystery (were kids killed 10 years ago by their principal, rather than the guy who was arrested?) and they end up getting trapped inside with the killer. There's a sizable body count and the gore effects are sometimes passable - though the fake blood is very pink - but the acting is unbelievably wooden. The director tried for some fancy cinematography which is occasionally interesting and there are a few imaginative deaths (the fire extinguisher being the most memorable). Overall, though, the film looks like it took a weekend to make and was done as a lark and there's nothing remotely entertaining going on here.