Gone by Michael Grant (YA Dystopian Novel)

Plot: There are teens, but not one single adult. Just as suddenly, there are no phones, no internet, no television. No way to get help. And no way to figure out what's happened. Hunger threatens. Bullies rule. A sinister creature lurks. Animals are mutating. And the teens themselves are changing, developing new talents—unimaginable, dangerous, deadly powers—that grow stronger by the day. It's a terrifying new world. Sides are being chosen, a fight is shaping up. Townies against rich kids. Bullies against the weak. Powerful against powerless. And time is running out: On your 15th birthday, you disappear just like everyone else...