Zombie Apocolypse

"It's not safe here." I said. "We need to leave before they come back."

We walked over to the door and looked through the peep hole.

"All clear." Bob shouted.

We rushed out of the building and watched for any movement.  Splash.  A small stone skittered across a rooftop and fell in a small puddle of water.  We aimed our guns up to the spot that it fell from.  Nothing moved.  Then a zombie fell off the roof and charge at bob.