Falling Skies by havel.b

The chaotic aftermath of an alien attack has left most of the world completely incapacitated. In the six months since the initial invasion, the few survivors have banded together outside major cities to begin the difficult task of fighting back. Each day is a test of survival as citizen soldiers work to protect the people in their care while also engaging in an insurgency campaign against the occupying alien force.
http://www.imdb.com/title/tt1462059/