We Kill Dead Things (Zombie Exterminators, Book One) by Sommer Marsden

Poppy thinks her life is weird working the food court at Parktowne mall, until in one brief moment of creeper killing, things change forever. Now she's a freelance zombie exterminator along with her long lusted after co-worker Garrity (her not-so-secret crush), a somewhat lusted after bad boy Cahill, and pretty gay boy Noah.

When the four are hired to do a ballsy zombie clean up at St. Peter's Hospital, Poppy finds out just what's more scary than creepers: The Evoluminaries, a zealot cult who think zombies are part of God's chosen, who happen to end up thinking Poppy might make a mighty good zombie incubator. She finds herself finally sleeping with Garrity, being hunted by a crazy preacher man and stumbling over the fact that Cahill and Noah have become lovers somewhere in the chaos. And that's all on the job.

Just another day in the life when you kill dead things...