Gone (book #1), MIchael Grant.

In the blink of an eye all the adults disappear in a small town in southern California and no one knows why. Cut off from the outside world, those that are left are trapped, and there’s no help on the way. Sam Temple and his friends must do all they can to survive.

Chaos rules the streets. Gangs begin to form. Sides are chosen – strong or weak.

Cruel or humane. And then there are those who begin to develop powers … … The GONE series is Lord of the Flies for the 21st century. In turns breathtaking, harrowing, and utterly terrifying.