By Jonathan Stempel and Nate Raymond

NEW YORK Sixteen people who witnessed a white supremacist kill 10 Blacks in a shooting last year at a Buffalo, New York grocery store have sued social media and firearms-related companies, to hold them liable for causing emotional trauma.

The complaint filed on Tuesday in a state court in Buffalo names as defendants YouTube and Reddit, where the gunman Payton Gendron was allegedly radicalized through exposure to harmful content, and learned information to help carry out his attack.

Also sued were three retailers--Mean Arms, Vintage Firearms and RMA Armament--that allegedly sold firearm equipment and body armor that Gendron used.

Alphabet and Google, which own YouTube, are also defendants, as are Gendron's parents. The civil lawsuit was filed by the nonprofit Everytown for Gun Safety.

A YouTube spokesman on Wednesday said the company had "deepest sympathies" for attack victims and families, has invested over the years to find and remove extremist content.

RMA's lawyer said he looked forward to vindicating his client in court, while calling the attack "reprehensible" and saying RMA "condemns everything the shooter stood for."

A lawyer for Mean Arms declined to comment. The other defendants did not immediately respond to requests for comment.

While the same defendants face other civil litigation over the May 14, 2022 attack at the Tops grocery store, Tuesday's lawsuit differs because the plaintiffs had not suffered serious physical injuries, or were related to people who did.

The plaintiffs include store employees and customers who said the shooting left them with long-lasting emotional distress, and symptoms including anxiety, depression, insomnia, lethargy and nightmares.

One plaintiff, Fragrance Harris Stanfield, said she was unable to return to work at Tops or as a substitute teacher in Buffalo schools, and has had panic attacks at stores when she could not locate an exit.

The plaintiff DennisJanee Brown said she feels uneasy at work in the presence of white people, while the plaintiff Rose Marie Wysocki said she has felt "enormous guilt and anger," feeling as though she survived because she was white.

Through the defendants' alleged negligence, Gendron "gained the racist motivation, tools and knowledge necessary for him to commit the mass shooting," the complaint said.

Gendron, 18 at the time of the attack, was sentenced in February to life in prison without parole, after pleading guilty to charges including murder and terrorism motivated by hate. New York does not have a death penalty.

(Reporting by Jonathan Stempel in New York and Nate Raymond in Boston; Editing by Aurora Ellis)