The FBI is warning about a criminal network targeting children. Officials say predators are befriending teenagers online then coercing them into sexual and violent behavior, including self-harm or even suicide. The online predators, part of the network known as "764," demand victims send them photos and videos of it all, so the shocking content can be shared with fellow 764 followers or used to extort victims for more. ABC News' Pierre Thomas has the latest. Read more: https://abcnews.go.com/US/