WATCH: Video shows man charge toward Buffalo grocery store mass shooter in court

See video of the courtroom incident here:

“You don’t know what we’re going through,” a man shouted as he was led away by court officers. For several minutes thereafter, family members hugged and calmed each other.

After about 10 minutes, Judge Susan Eagan ordered Gendron back in and let the proceeding resume, admonishing everyone to “conduct ourselves appropriately.”

Watch: Buffalo supermarket shooting: 911 dispatcher who hung up on employee fired

“I understand that emotion, and I understand the anger, but we cannot have that in the courtroom,” she said.

Gendron pleaded guilty in November to charges including murder and domestic terrorism motivated by hate. The terrorism charge carries an automatic life sentence.

Moments earlier, Kimberly Salter, the widow of security guard Aaron Salter, explained why she and her family were wearing black and red.

“Red for the blood that he shed for his family and for his community, and black because we are still grieving,” she said as her husband’s killer, Payton Gendron, looked directly at her from the defense table.

Gendron pleaded guilty in November to charges including murder and domestic terrorism motivated by hate. The terrorism charge carries an automatic life sentence.

Relatives of several victims are expected to speak during the hearing, giving them an opportunity to address the judge and the killer responsible for their sorrow.

Gendron, now 19, wore bullet-resistant armor and a helmet equipped with a livestreaming camera as he carried out the May 14 attack. He killed his victims with a semiautomatic rifle, purchased legally but then modified so he could load it with high-capacity ammunition magazines that are illegal in New York.

There were only three survivors after he shot 13 people, specifically seeking out Black shoppers and workers.

Read: Buffalo supermarket mass shooting: Victims list released by Buffalo PD

His victims at Tops Friendly Market included a church deacon, the grocery store’s guard, a neighborhood activist, a man shopping for a birthday cake, a grandmother of nine and the mother of a former Buffalo fire commissioner. The victims ranged in age from 32 to 86.

In documents posted online, Gendron said he hoped the attack would help preserve white power in the U.S. He wrote that he picked the Tops grocery store, about a three-hour drive from his home in Conklin, New York, because it was in a predominantly Black neighborhood.

While a life prison sentence is guaranteed for Gendron, he also faces separate federal charges that could carry a death sentence if the U.S. Justice Department chooses to seek it. New York state does not have the death penalty.

Gendron’s admission of guilt on the state charges is seen as a potential help in avoiding a death sentence in the penalty phase of any federal trial. In a December hearing, defense attorney Sonya Zoghlin said Gendron is prepared to enter a guilty plea in federal court in exchange for a life sentence.

The mass shooting in Buffalo, and another less than two weeks later that killed 19 students and two teachers at a Texas elementary school, amplified calls for stronger gun controls, including from victims’ relatives who traveled to Washington, D.C. to testify before lawmakers.

New York legislators quickly passed a law banning semiautomatic rifle sales to most people under age 21. The state also banned sales of some types of body armor.

Watch: Michigan State University shooting: 3 dead, 5 injured; suspect dead

President Joe Biden signed a compromise gun violence bill in June intended to toughen background checks, keep firearms from more domestic violence offenders and help states put in place red flag laws making it easier for authorities to take weapons from people adjudged to be dangerous.

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