The Slumber Party Massacre (1982)

An eighteen-year-old high school girl is left at home by her parents and she decides to have a slumber party. There is friction between some of the invited guests and the new girl, who is better at basketball than they, so the new girl decides to stay at home (which is conveniently across the street from the host's house). Meanwhile, a murderer of five people with a propensity for power tools has escaped and is at large, and eventually makes his way to the party, where the guests begin experiencing an attrition problem, with only the new girl to help them.—Ed Sutton