Kenzie was the one who locked Johnny into a shed and then attacked him, knocking him to the floor and then stabbing him to death.
Kenzie then watched as Amy and Naoise got into a fight and Amy stormed off. Kenzie struck the swingball so hard that it hit Naoise and knocked her down. Kenzie then stabbed her to death.
After Martha had killed Katie and Amy, she and Kenzie met to discuss their killings. The two had planned to kill each other, but Kenzie overpowered Martha and smothered her to death before commiting suicide with a shotgun.