Absolutely. Especially if your players, like mine, have a tendency to default to "call the cops and run" whenever something funny was going on. If your particular system has mechanics for rewarding them for acting in-genre (IE, "Let's split up, gang!"), encourage it to the hilt.Make sure that hiding is not an option and force the players to make a decision to do something. If you can just hide from the threat then it's not really a threat at all. Make sure the players place of safety is violated or unsafe in some other way. Force them to leave it or rather make the option of staying worse than the option of leaving.