Warning: The following contains details that some might consider graphic in nature. 

CONKLIN, N.Y. – Accused Buffalo mass shooter Payton Gendron planned his allegedly racially motivated attack down to the minute – or at times, even the second – ahead of Saturday’s massacre that left 10 people dead and 3 others injured, according to local reports and the suspect’s alleged manifesto. 

Gendron, 18, appeared to have planned to unleash his horrific attack at a Tops Friendly Markets on Jefferson Avenue around 4 p.m. Friday – which he said he had determined was the busiest time of day, according to his 180-page manifesto. It’s unclear, then, why he instead allegedly did so on Saturday afternoon. 

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Payton Gendron

Payton Gendron (Erie County DA / AP Photo)

In the days since Saturday’s events, high-ranking law enforcement officials, including FBI Director Christopher Wray and U.S. Attorney General Merrick B. Garland, have undisputedly called the tragedy "a hate crime and an act of racially-motivated violent extremism."

According to multiple reports and the manifesto itself, Gendron allegedly planned to have corn beef hash for breakfast and leave his home around 7:30 a.m. in normal clothes. 

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He planned to arrive at the Tops location around noon and case the inside of the store to "make sure everything is as expected." 

He planned to eat food at McDonald’s and then, around 3:30 p.m., to change into his military-style attire. He allegedly designated a parking space on Sherman Street where he planned to do so.

Gendron then allegedly planned to publish his writings regarding the attack 10 minutes before he planned to go inside around 4 p.m. He planned to start a livestream around 3:55 p.m., and then turn into the store parking lot at 3:58 p.m., the manifesto states. 

He allegedly planned where he would stop his vehicle in front of the store when he pulled up around approximately 4 p.m., and estimated it would take him "between 2-3 seconds" to "kick open the door and jump out of my car." 

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Gendron also drew a diagram of the store, which he allegedly included in the manifesto, and outlined in horrifying detail his plans to launch his attack. 

buffalo mass shooting suspect payton gendron

People pay their respects outside the scene of a shooting at a supermarket in Buffalo, N.Y., Sunday, May 15, 2022.  (AP Photo/Matt Rourke)

He allegedly estimated he would leave the store around 4:04 p.m. and then continue his attack by opening fire on people on the streets and nearby. 

Gendron planned that he would either surrender to police or continue his attack if he were to find another location, the manifesto states. 

Speaking to law enforcement and private community members during a Monday afternoon partner call, FBI Buffalo Special Agent-in-Charge Stephen Belongia said the investigation to confirm "with certainty" that the document "belongs to or was created by the alleged killer" was ongoing.

"However, it is noted clear that the manifesto included specific details of this object, including reconnaissance gear descriptions and weapons that are consistent with other evidence collected thus far," Belongia told the group. "In addition, evidence collected to date about the alleged killer's motivation is consistent with the manifesto."

Wray, United States Secretary of Homeland Security Alejandro Mayorkas and Associate Attorney General for the Department of Justice Civil Rights Division Kristen Clarke also participated in Monday’s call. 

Belongia further noted that the manifesto claimed the alleged killed was working alone and was not a member of a political group or organization, and that he claims in the document that he is a white supremacist. 

Gendron allegedly claimed in the manifesto that he chose the Buffalo Tops store because of its demographic breakdown as having "the highest black percentage that is close enough to where I live."

Instead of opening fire on the store on Friday as he had allegedly planned to do, Gendron instead sat outside the supermarket for hours on Friday. 

On Friday, Gendron was wearing "camper gear on his back like he was asking people for change" and the same camouflage clothing he was seen in on Saturday, Tops operations manager Shonnell Harris Teague told ABC News

Gendron sat outside the supermarket for hours on Friday, but entered the store later in the day, when he appeared to be pestering shoppers, Teague told ABC.

People gather outside the scene of a shooting at a supermarket in Buffalo, N.Y., Sunday, May 15, 2022. 

People gather outside the scene of a shooting at a supermarket in Buffalo, N.Y., Sunday, May 15, 2022.  (AP Photo/Matt Rourke)

"I asked him can he please leave the store – you're gonna have to stand outside," she told ABC.

Then, Gendron, who is White, pulled up to the Tops grocery store around 2:30 p.m. Saturday and immediately began firing off shots – wounding four people in front of the market before making his way inside, Buffalo Police Commissioner Joseph Gramaglia said. Three of the four victims died. 

Once inside, he exchanged fire with store security guard Aaron Salter, who was a retired police officer, officials have said. Salter fired several rounds at Gendron before the suspect fatally shot him, Gramaglia said.

Gendron then allegedly made his way around the store shooting several other victims. When confronted by police, Gendron placed the rifle to his neck before dropping the weapon and surrendering, the police chief said. 

Ten people were shot and killed. Three other people were injured.

Eleven of the victims were Black individuals, officials have said. 

The deceased victims have been identified as: Roberta A. Drury, 32; Margus D. Morrison, 52; Andre Mackneil, 53; Aaron Salter, 55; Geraldine Talley, 62; Celestine Chaney, 65 ; Heyward Patterson, 67; Katherine Massey, 72; Pearl Young, 77; and Ruth Whitfield, 86.

Officials have said the suspect live-streamed a portion of the shooting on social media platform Twitch. A Twitch spokesperson said the stream was suspended within two minutes. 

So far, investigators have found that Gendron was in possession of "three weapons. There were two in the car and one in his possession," Gramaglia said. 

"One was a rifle, one was a shotgun … He had an AR-15" inside the store with him, the commissioner added.

Gendron was charged with first-degree murder. He was arraigned late Saturday and pleaded not guilty. He was ordered held without bail and is due back in court on Thursday. 

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A spokesperson for the Erie County District Attorney's office would not comment when asked whether Gendron's parents faced charges related to the circumstances of the attack.