Scene of a shooting at a TOPS supermarket in Buffalo, New York
Scene of a shooting at a TOPS supermarket in Buffalo, New York REUTERS/Brendan McDermid

A document posted online by the suspected shooter in the Buffalo supermarket massacre this past Saturday detailed his initial plans weeks before the shooting, The Hill reported on Monday.

According to the document, obtained by the Washington Post, Payton Gendron refers to the local Tops supermarket as “attack area 1,” also noting two other areas in the city where he can “shoot all blacks.”

The document was based on a recent trip Gendron took to the city ahead of the massacre, in which he detailed travel paths to each location, the timing he needs if he was involved in a shootout with authorities, and estimated the total number of Black people he will kill during the planned scenario.

Gendron’s 589-page document was published on the filesharing platform MediaFire on April 29, and a compilation of messages of the document was also posted on the social media platform Discord, where Gendron went under the widely used username of “jimboboiii,” according to the Post.

The document also noted that Gendron was confronted by the supermarket’s security guard in March when the security guard asked Gendron about his plans.

“I’ve seen you go in and out … What are you doing?” the security guard asked Gendron. Gendron replied that he was at the supermarket “collecting consensus data” on the store before making an excuse to leave for his vehicle.

Gendron also added in his document numerous photos of himself using various social media handles, which included images of his daily life such as him obtaining a speeding ticket, the Post reported.

10 people were killed and three more wounded in Saturday’s shooting, when the gunman opened fire at the Tops Friendly Markets, firing a shotgun and two rifles during a six-minute rampage.

Gendron surrendered to police after the shooting, and he has been charged with 10 counts of first-degree murder.

Prior to the shooting, Gendron uploaded a manifesto to the internet, warning of “white genocide”, citing low birthrates among people of European heritage across the globe, and higher birthrates among non-white populations.

US President Joe Biden and First Lady Jill Biden will travel on Tuesday to Buffalo where they are expected to "grieve with the community that lost ten lives in a senseless and horrific mass shooting."