Going for the Kill
Now that you have spotted someone, run straight for them. To attack as the killer, you simply need to get close enough and you will swing automatically.
You can choose to stay by the incapacitated survivor to ensure nobody revives them, but this will leave time for the other survivors to find switches. You should stay on the move and try to find as many as you can.
Remember that you still win if you can run the clock out, so it is OK if one of the survivors manages to revive the others.