Suspected Buffalo gunman Payton Gendron’s plan was shared online shortly before the attack

The alleged Buffalo supermarket shooter shared his rambling plans for his deadly racist attack half an hour before gunning down 10 people on Saturday, a new report says.

Payton Gendron, 18, invited people to a private chat on the Discord app, who revealed his views on white supremacists and outlined how he’d scouted the Tops Friendly Markets in a lunatic scheme to kill as many black people as possible, reported CNN.

“What we know at this point is that the suspect created a private invitation-only server to serve as a personal diary chat log,” a Discord spokesperson told CNN.

“However, about 30 minutes before the attack, a small group of people were invited to the server and joined it. Before that, our records show that no other people saw the diary chat log on this private server.”

It’s not clear how many people Gendron, who is white, invited to the private chat room or how many people viewed the content before it was removed. A Discord spokesperson didn’t respond to an email from The Post on Wednesday.

Thousands of chat entries made up a months-long online diary that was later shared more widely on 4Chan, an online message board that Gendron said encouraged his racist extremism.

“Every time I think maybe I shouldn’t commit to an attack, I spend 5 minutes [on] /pol/ then my motivation returns,” Gendron wrote in one post, referring to a political part of 4Chan.

He also used the diary to describe how he cruelly stabbed and then decapitated a feral cat at his home in Conklin, NY – prompting him to post a photo of his blood-splattered face.

Gendron has pleaded guilty to one murder in the deadly shooting in Buffalo, a town 200 miles from his small, mostly white hometown.

The suspected gunman is accused of shooting dead a total of 13 people during his rampage, which he live-streamed on Twitch while wearing military-style tactical gear including body armor.

Eleven of the victims were black, while two were white, authorities said.

New York Attorney General Letitia James said Wednesday her office will investigate Discord, Twitch, 4chan and other platforms the shooter “used to amplify the killing spree.”

“My office is investigating the social media companies that the Buffalo assassin used to plan, facilitate and stream his terrorist attack,” she wrote on Twitter.

“This terrorist attack has revealed the depth and dangers of these platforms that spread and promote hate without consequences. We are doing everything in our power to stop this dangerous behavior now and ensure it never happens again.”