Videos of attacks are designed to amplify the terror, of course. But what makes this atrocity “an extraordinary and unprecedented act of violence,” as Prime Minister Jacinda Ardern described it, is both the methodical nature in which the massacre was conducted and how it was apparently engineered for maximum virality.

Though platforms like Facebook, Twitter, and YouTube scrambled to take down the recording and an accompanying manifesto from the gunman, they were no match for the speed of their users; new artificial-intelligence tools created to scrub such platforms of terrorist content could not defeat human cunning and impulse to gawk. In minutes, the video was downloaded and mirrored onto additional platforms where it ricocheted around the globe. Still frames of bodies were screenshotted and uploaded to sites like Reddit, 4chan and Twitter where it was shared and reshared…

Internet users dredged up the alleged shooter’s digital history, preserving and sharing images of his weapons and body armor. The gunman’s digital footprint — from the rantings of his White Nationalist manifesto to his 8chan message board postings before the murders — was unearthed and, for a time, distributed into far-flung corners of the web.