3.

After a lot of aimless roaming, they stumbled, completely by accident, upon the small-town in Oregon.

Well, they didn't actually find the town, but they did run headfirst into the crazy, sci-fi force field that surrounded the town. Well they'd stood around, trying to figure what the hell had happened, a group of black clad men and women with absolutely crazy looking guns appeared on the other side of the force field.

After much debate, they were allowed in and hustled off to have blood tests and about a dozen other medical exams run on them. Once those were completed, they were shocked to find the town almost unchanged by the zombie apocalypse, completely self-sufficient with its own food power and water supply.

Most of the citizens were wandering around doing their jobs and various tasks as though nothing had happened.

As they stood there in varying degrees of shock of lawn man in a tan Sheriff's uniform approached and said, "Welcome to Eureka."