Devil Times Five (1974) 
A fairly effective and creepy 'killer kids' film, Devil Times Five deals with 5 sociopathic children who escape their psychiatric transportation and end up being taken in by some unwitting people who are holidaying nearby.
The children are able to lure the adults into a false sense of security with their feigned sweet and innocent behaviour before the film takes a darker turn and the crazed kids start dispatching their contemporaries in various creative and brutal fashions, but without losing their lighthearted and playful air, which makes it all the more disturbing and compelling.
The holidaying adults certainly have their own particular issues too, to the extent that when watching them perish at the hands of the psychotic children, you can't help but feel less than sorry for some of them.
Certainly a stand-out film in this particular sub-genre, Devil Times Five is a entertaining oddity that's worth checking out.
Originally posted here:
Nightmare USA Films Discussion Thread