Earth - The Elemental Series, #1

Shayna and her two best friends have the ability to manipulate and control the four elements of earth, air, water and fire. While learning to hone their growing powers, they discover a new and malicious presence in their sleepy beach town. Someone is performing blood magic and threatens to expose their small magical community. So far only small animals have been slaughtered, a clear indication of an amateur, but then the nightmares start.
Shayna suffers nightmares of being chased and sacrificed only to wake up bloodied and bruised. She thinks her magical blood is the ultimate target for the final blood rite. When an innocent girl, Tracy, is kidnapped Shayna knows it's only a ploy to draw her out; she can't let someone die because of her.