Horror House/The Haunted House Of Horror (1969) | HORROR/SLASHER | FULL MOVIE

A group of 1960's teenagers bored with the party they're at drive out to a deserted old mansion, but their laughter turns to fear when one of them is killed in a frenzied knife attack. Another of them persuades the rest that they should solve the murder themselves rather than go to the police, not surprisingly opening the way to further carnage.

IMDb: https://www.imdb.com/title/tt0064443