The rest of the story:

The next day after the opening scene the teens come to school the next day, they are too traumatised to tell anyone, they won’t dare to because they are scared of the scientist. The 3 that are left during the day get taken, but the audience will not see the disappearance of people that are left. They are found later in the lunch time by the rest of the friends who went in the woods and see them hanging. Strangled by Bunsen burners for an evil twist. Most of the school ends up disappearing.