(NBC News) — The 18-year-old suspected of targeting and fatally shooting 10 Black people in Buffalo, New York, wrote in what are believed to be his online journals that he learned how to illegally modify his rifle by watching YouTube videos. The suspect appeared to link to the videos in Discord chat logs, and the videos were still available on YouTube as of Thursday evening — five days after the shooting.

Some of the videos appear to violate YouTube’s community guidelines banning videos that show how to install gun accessories like high-capacity magazines.

The advocacy group Everytown for Gun Safety Support Fund is calling on YouTube to strengthen how it enforces its gun policies in response to the journals and videos.

“Technology platforms, such as YouTube, have a responsibility to users and the public at-large to ensure that posts do not incite violence or promote extremist content,” the group wrote Thursday evening in a letter to YouTube. 

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