An 18-year-old white man was charged with first-degree murder in the Buffalo mass shooting that police said was racially motivated

• A suspect in the Buffalo mass shooting was charged with first-degree murder on Saturday.
• The teen pleaded not guilty in the attack, which police said was racially motivated.

An 18-year-old white man has been charged with first-degree murder in connection to a mass shooting at a Tops grocery store in Buffalo, New York, on Saturday that police said was racially motivated and left 10 people dead.

The suspect — a Conklin, New York resident — was arraigned in Buffalo City Court Saturday evening. He pleaded not guilty.

The teen is being held in jail without bail and is due to appear at a felony hearing in five days, according to Erie County District Attorney John Flynn.

"We have taken the appropriate steps right now to get him behind bars," Flynn said at a press conference, adding that a first-degree murder conviction could result in life in prison without parole.

The shooting suspect appeared before the court in a mask and handcuffs, according to images shared on social media by reporters present.

Federal officials said during a press conference earlier in the day the attack was being investigated as a hate crime and an act of "racially motivated violent extremism."

Of the 13 people that were shot, 11 were Black and two were white.

Police said the gunman in the shooting arrived in heavy tactical gear at the Tops grocery store at around 2:30 p.m. on Saturday before opening fire in the parking lot and then inside the store.

The gunman was confronted by a security guard who was a former police officer, but the guard's bullets did not penetrate the shooter's armor, police said. The security guard was killed in the attack.

The gunman was holding his gun to his neck when police engaged him and convinced him to lower his weapon, remove his tactical gear, and surrender, authorities said.

Officials alleged the shooting suspect used a camera attached to his tactical helmet to livestream the attack. Twitch confirmed the attack was live-streamed on its platform but said it was taken down within two minutes of the start of the violence.

At least 15 police cars were parked outside the shooting suspect's home in Conklin, New York, on Saturday night, local WSYR reporter Andrew Donovan reported.

A manifesto belonging to the suspect outlined plans to kill Black people and referenced replacement theory, a conspiracy theory popular with white supremacists that claims whites are being replaced by people of color, a federal official confirmed to The New York Times.

Known as the "Great Replacement" theory, the concept is well-known among the far-right and has been cited as motivation for violence in the past.

The manifesto, which was posted online ahead of the shooting, included detailed plans to execute the attack, the official said, including the rifle the suspect planned to use and a detailed timeline of the day, including plans to first shoot the security guard near the store's entrance before proceeding to shoot Black shoppers inside.

The teen suspect wrote in the manifesto the location for the shooting was chosen because it had the highest percentage of Black residents near his home, which authorities said was located hours away from the crime scene, The Times reported.

The outlet said he also wrote he was inspired by other mass shooters, including the man who killed nine Black church members during a Bible study session in South Carolina in 2015.