Officials stated on Sunday that the 18-year-old white male who fatally shot ten people in a Buffalo supermarket researched the neighborhood demographics and arrived a day early to perform surveillance to kill as many Black people as possible.

According to investigators, the racially motivated attack occurred a year after the gunman was brought to a hospital by State Police after making threats against his high school.

Police said he wasn't charged with a crime and was released from the hospital after a day and a half, but the revelation raised questions about his access to guns and whether he could have been under stricter law enforcement surveillance.

The attack in Buffalo elicited sorrow and rage in the primarily black area surrounding Tops Friendly Market. A group gathered there on Sunday afternoon to lead chants of "Black lives matter" and lament the deaths of two Black victims, including an 86-year-old widow who had just returned from seeing her husband in a nursing facility and a supermarket security officer.

Reverend Denise Walden-Glenn stated, "Someone filled his heart with so much hatred that he would devastate and destroy our community."

At the National Peace Officers Memorial event at the US Capitol, President Joe Biden stated, "We must all work together to address the hatred that remains a stain on the American soul." Later, the White House noted that the president and first wife would visit Buffalo on Tuesday to "share the community's sorrow."

The attack in Buffalo was the deadliest of numerous shootings around the nation in recent days. Officials in Milwaukee enforced a curfew after 21 people were injured in three separate shootings in an entertainment zone where hundreds congregated for an NBA playoff game on Friday night. Three individuals were killed over the weekend in three further shootings in a city in the Midwest.

On Sunday, two shootings — one at a flea market in Houston and the other at a church in California — resulted in three fatalities and many injuries.

As the nation reeled from the Buffalo incident, more information about the shooter's past and Saturday's rampage, which he live-streamed on Twitch, emerged. Kathy Hochul, a Buffalo native and the governor of New York, asked to know whether technology corporations have done "everything humanly possible" to monitor violent content as soon as it arises.

"If not, I will hold you accountable," she declared.

Twitch stated in a press release that the program was terminated "less than two minutes after the violence began."

According to the New York State Police, troopers were dispatched to Payton Gendron's high school in early June 2017 after reporting that a 17-year-old student had made threatening statements.

An unnamed law enforcement official stated that Gendron threatened to carry out a shooting at Susquehanna Valley High School in Conklin, New York, around graduation. The official was not allowed to discuss the probe publicly.

After being released from the hospital, Gendron had no further contact with law enforcement, according to Buffalo Police Commissioner Joseph Gramaglia.

"Nobody called in," he claimed. "No complaints were received," Gramaglia stated.

A person is prohibited from possessing a firearm under federal law if a judge has concluded they have a "mental defect" or if they have been committed to a mental institution. However, an evaluation alone does not trigger the ban.

Federal investigators were still attempting to validate the integrity of Gendron's 180-page paper allegedly produced that outlined his attack plans and motivations for carrying them out.

A law enforcement official told AP that a preliminary investigation uncovered Gendron's repeated visits to websites promoting white supremacist ideologies and race-based conspiracy theories and his extensive research on the 2019 mosque shootings in Christchurch, New Zealand, and the 2011 summer camp massacre in Norway.

The official stated that federal authorities executed various search warrants and interrogated Gendron's parents, cooperating with investigators.

In less than one minute, the gunman fired volley after volley of gunfire as he sped through the parking lot and entered the store, pausing briefly to reload. Towards one point, he aims his gun at a white individual hiding behind a cash register, but he apologizes and does not fire.

Screenshots claimed to be from the broadcast appear to show a slur against Black people, and the number 14 scribbled on his gun, possibly referencing a white supremacist motto.

Saturday, according to authorities, he shot a total of eleven Black victims and two white persons.

On Sunday, Buffalo Mayor Byron Brown stated, "This individual came here with the specific intent of taking as many Black lives as possible."

The lengthy statement ascribed to Gendron articulated a racist philosophy based on the notion that white people should only inhabit the United States. The paper stated that all others were "replacers" who should be exterminated through force or intimidation. It was noted that the purpose of the attack was to terrify non-white, non-Christian individuals into leaving the country.

According to the paper, Gendron selected his target based on demographic analysis and chose a Buffalo neighborhood with a high proportion of black residents.

According to authorities, Gendron went approximately 200 miles (320 kilometers) from his home in Conklin, New York, to Buffalo to commit the crime.

Gramaglia stated that the suspect did surveillance of the store and surrounding area the day before the incident, on Friday.

Gendron surrendered to police, who confronted him in the supermarket's foyer and persuaded him to drop the weapon he had wrapped around his neck. He was arraigned on a murder charge Saturday evening, wearing a paper gown before the judge.

The Buffalo incident was merely the most recent act of mass violence in a nation rattled by racial tensions, gun violence, and recent hate crimes. A month later, ten people were injured in a shooting on the Brooklyn subway, and just over a year later, ten people were killed in a supermarket massacre in Colorado.

"There's too much. I'm attempting to be a witness, but it's simply too much. "You can't even go to the store in peace," Yvonne Woodard, a resident of Buffalo, told the Associated Press. "It's insane."