Buffalo mass shooting suspect “was scouting the supermarket” and targeted its specific zip code, authorities say

Payton Gendron, the 18-year-old man who allegedly shot and killed 10 people at a Buffalo supermarket Saturday afternoon, was motivated by hate, authorities said. He was charged with first degree murder Saturday, Erie County District Attorney John J. Flynn said in a news release, and has pleaded not guilty.

Here’s what we know about the shooting suspect:

Investigators were reviewing a 180-page purported manifesto that was posted online in connection with the shooting probe, two federal law enforcement sources told CNN on Saturday.

The manifesto, independently obtained by CNN shortly after the attack and before authorities released the suspect’s name, is allegedly written by a person claiming to be Payton Gendron confessing to the attack.

The manifesto’s author says he bought ammo for some time but didn’t get serious about planning the attack until January. The author also goes on about his perceptions of the dwindling size of the White population and claims of ethnic and cultural replacement of Whites.

A portion of the document is written in question-and-answer form.

The manifesto’s author attributes the internet for most of his beliefs and describes himself as a fascist, a White supremacist and an anti-Semite.

Authorities say when the suspect arrived at the store around 2:30 p.m., he was heavily armed, wearing tactical gear, a helmet and had a camera that was livestreaming his actions.

The suspect used an assault weapon, Flynn said during the news conference.

The popular livestreaming platform Twitch confirmed Saturday that the shooting suspect used its platform to stream a live broadcast during the attack.

Gendron was arraigned Saturday evening before Buffalo City Court Chief Judge Craig Hannah on one count of first-degree murder, the district attorney’s news release said.

He pleaded not guilty, Hannah told CNN. If convicted, he faces a maximum sentence of life in prison without parole, the release said.

Gendron is set to return to court on the morning of May 19 for a felony hearing, the release said. He will remain in custody without bail, it added.

CNN’s Sharif Paget, Sabrina Shulman and Brian Stelter contributed to this report.