Running from zambie's

It all starts in an orphanage. Four best friends (who act like sisters) who would literally kill for each other, and might even have too actually kill a couple things, get somehow stuck in the middle of an apocalypse.

The four of them leave the orphanage in hopes of finding shelter but instead of finding shelter....they might find something else.

They run for about a day and they find five guys, and there little sister.

Five girls, and five guys with there little sister.

Doesn't quite add up does it.