Sickening manifesto emerges of San Diego mosque shooters Cain Clark and Caleb Vasquez

New disturbing details have emerged about the May 18 massacre at a San Diego mosque, and the two deranged teenage shooters who allegedly livestreamed the carnage and left behind a vile manifesto.

Why did Cain Clark and Caleb Vasquez open fire on the Islamic Center of San Diego, the largest mosque in the city? Here’s what you need to know.