NYPD: Penn Station suspect says he runs white supremacist Twitter group

Penn Station arrests

Mayor Eric Adams said social media posts that a man made about attacking a synagogue were "not an idle threat." Authorities arrested a man from Manhattan and a man from Long Island early Saturday.

NEW YORK – Social media posts about attacking a synagogue represented a real danger to the city's Jewish community, Mayor Eric Adams said Monday.

"This was not an idle threat," Adams said at a news conference where he was joined by officials from the FBI, the Metropolitan Transportation Authority and other agencies involved in the arrests early Saturday of Christopher Brown and Matthew Mahrer on charges including criminal possession of a weapon. The men were arrested at New York's Penn Station after authorities spotted the posts.

"This was a real threat," he said.

According to the criminal complaint against him, Brown made a series of threats on Twitter including, on Thursday, "Gonna ask a Priest if I should become a husband or shoot up a synagogue and die," and then on Friday, "This time I'm really gonna do it."

This was not an idle threat. This was a real threat. Mayor Eric Adams

Authorities linked the tweets to Brown, of Aquebogue, on Long Island, and identified Mahrer, of Manhattan, as an associate, said Michael Driscoll, head of the FBI's New York office.

A description of Brown, 21, and Mahrer, 22, went out to law enforcers, and two MTA police officers spotted the two at Penn Station late Friday and arrested them, police said. Man accused of making threats against NYC Jewish community charged

Brown had a large military-style knife, a ski mask and a swastika arm patch when he was arrested, authorities said.

A bag containing a Glock-style pistol with a large-capacity magazine and 17 bullets was seized from Mahrer's apartment building, according to the complaint. Surveillance video from shortly before their arrests showed Brown and Mahrer walking into the building, with Mahrer carrying the bag, according to the criminal complaint.

Brown, who was charged with making a terrorist threat in addition to the weapons charges, told police that he runs a white supremacist Twitter group and Mahrer is one of his followers, according to the complaint.

"I have Nazi paraphernalia at my house. I think it is really cool," Brown told police, the complaint said.

Brown said he and Mahrer met at St. Patrick's Cathedral before buying a gun because he "wanted to get the blessing," according to the complaint.

I have Nazi paraphernalia at my house. I think it is really cool. Christopher Brown, according to criminal complaint

Both men were arraigned in Manhattan criminal court over the weekend and are due back in court on Wednesday. Federal charges against them could be filed at a later time, Driscoll said.

Phone messages seeking comment were left with attorneys for Brown and Mahrer. New Jersey teen charged with threatening to attack synagogues

Adams, a Democrat and a former police officer, said threats against Jewish people or any other group must be taken seriously after attacks like the Buffalo supermarket shooting and Saturday's shooting at an LGBTQ nightclub in Colorado Springs.

"America must defeat the rising threat of domestic terrorism," Adams said. "It is real, it is here and we must have a formidable approach to it."