Almost immediately, people copied and reposted versions of the video across the internet, including on Reddit, Twitter, and YouTube. The shooter apparently seeded warnings on Twitter and 8chan before livestreaming the rampage on Facebook for 17 gut-wrenching minutes. At least 49 people were murdered Friday at two mosques in Christchurch, New Zealand, in an attack that followed a grim playbook for terrorism in the social media era.
