Glass Houses by Rachel Caine

What's on the back of the book:
Welcome to Morganville.
Just don't stay out after dark.

Morganville is a small town filled with unusual characters - when the sun goes down, the bad come out. In Morganville, there is an evil that lurks in the darkest shadows - one that will spill out into the bright light of day.

For Claire Danvers, high school was hell, but college may be murder. It was bad enough that she got on the wrong side of Monica, the meanest of the school's mean girls, but now she's got three new roommates, who all have secrets of their own. And the biggest secret of all isn't really a secret, except from Claire: Morganville is run by vampires, and they are hungry for fresh blood . . .

A piece from the book:
Shane was in the doorway, ready for action, when Eve screeched the car to a stop; if he was still mad, at least he wasn't letting it get in the way of a good fight. Eve frantically signalled for him to stay where he was, on safe ground, and checked the street on all sides.
'Do you see anything?' she asked Claire anxiously. Claire shook her head, still sick. 'Damn. Damn! OK...but you know the drill, right? Asses and elbows. Bail!'
Claire fumbled open the lock, bolted out of the car, and hit the sidewalk running. She heard Eve's door slam and running footsteps. Deja vu, she thought. Now all they needed was for Brandon to show up and act like a total asshole...
She nearly ran into Shane as she pelted across the threshold; he stepped out of the way in time, just far enough to let her pass, and grabbed Eve to pull her inside as he slammed the door and locked it.
'You have got to get a better job,' he said. Eve wiped at her ruined make-up with the back of one hand and threw him a filthy look.
'At least I have a job!'
'What, professional blood donor? Because that's all you're going to be if you -'
Claire turned, ran into a vampire, and screamed her lungs out.
OK, so she wasn't a vampire. That was established in about thirty more seconds by a combination of Shane doubling over with laughter, the vampire screaming in fright and cowering, and - last of all - Eve saying, in blank surprise, 'Miranda! Honey, what the hell are you doing here?'