WHAT MOVIE IS THIS?

I need help trying to find this movie, heres what I remember.

Some kids go on vacation, and when they go back to their home town, the army or something has taking over their town. One bit I remember is all of them hiding in a barn at one of their houses, and one of their dogs is outside, and a boy goes out to get it, when a spaceship or helicopter is searching for them, and he nearly gets caught.

If you know it, please tell me :D

Thanks!