As many as 15 people joined the Buffalo shooting suspect Payton Gendron‘s private Discord app chatroom, about 30 minutes before the racist rampage, reports CNN.

A source with knowledge of Discord’s internal investigation confirmed to the outlet that Gendron sent out an invitation to a small handful of users to view his chat logs on the instant messaging app.

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“A private, invite-only server was created by the suspect to serve as a personal diary chat log,” said the Discord spokesperson on Tuesday. “Approximately 30 minutes prior to the attack, however, a small group of people were invited to and joined the server. Before that, our records indicate no other people saw the diary chat log in this private server.”

“As soon as” the communications app was made aware of the chatroom after the shooting, they removed it and any related content, the spokesperson said.

In the chat log, the suspect detailed his three reconnaissance visits to the Tops supermarket on March 8 to study the layout of the store. Additionally, he wrote he was able to pinpoint the grocer’s busiest times using the Google Maps graph feature “popular times” to know when to carry out the terrorist attack.

Many officials have turned their attention to condemn the social media platforms many white supremacist shooters before Gendron have used to spew their message of hate.

New York Attorney General Letitia James said on Wednesday that her office will open an investigation into the social networks Gendron used to plot the assault, including Twitch, the app he used to livestream the atrocity, and online forums 4Chan, 8Chan, and Discord.

“My office is launching investigations into the social media companies that the Buffalo shooter used to plan, promote, and stream his terror attack,” she wrote on Twitter.

Source: 15 People Joined Suspected Buffalo Shooter’s Private Chatroom Right Before Massacre