The Mogadorians - Alien Species - I am #4 by Pittacus Lore

An evil alien species, they attacked the planet Lorien when they knew it was at its most vulnerable. The planet’s Elders were gone, and the attack came out of nowhere. The Lorien were unprepared and hardly stood a chance. It was during the attack that the nine alien teens escaped, along with their guardians. But the Mogadorians won’t be satisfied until every last Lorien is killed, and they are now on Earth hunting the nine remaining teens one by one.

Mysterious alien identities. Newly discovered paranormal powers. Unexpected romance. From HarperCollins, the Lorien Legacies by Pittacus Lore—I AM NUMBER FOUR, THE LOST FILES: SIX'S LEGACY, and THE POWER OF SIX—is a thrilling new series about a group of teens struggling to outrun their past, discover their future, and live a normal life on Earth. Deadly Mogadorian aliens threaten the very existence of John Smith, also known as Number Four. Originally from the planet Lorien, John is on the cusp of developing powers. These are legacies from his ancestors that will allow him to fight the battle of a lifetime. But John is torn between his Lorien destiny and the love he never thought he could have with a human girl. Michael Bay, director of Transformers, calls Number Four "a hero for this generation."