(CNN) — The FBI in Newark, New Jersey, said Thursday afternoon it has received “credible information of a broad threat to synagogues” in the state, according to a tweet from the office.

“We ask at this time that you take all security precautions to protect your community and facility. We will share more information as soon as we can. Stay alert. In case of emergency call police,” the post said.

In a second tweet, the agency said it was taking a “proactive measure” with that warning, while “investigative processes are carried out.”

An online posting with antisemitic comments in a forum that is frequented by extremists is what prompted the FBI’s alert, a law enforcement source told CNN. While no specific target, timing or plan was mentioned, the nature of the post created enough concern on the part of the FBI that the agency decided to put a general warning out of an abundance of caution, the source said.

Part of that concern, the source added, comes because of previous mass killings involving extremists who posted on social media, including the 2018 Pittsburgh synagogue killings, the deadliest attack on Jewish people on US soil; the 2019 mass shooting in El Paso, Texas, the deadliest attack on Latinos in modern US history; and the May massacre at a Buffalo supermarket, an attack which officials said was racially motivated.

Thursday evening, the FBI said it takes all threats seriously and was working with law enforcement to investigate the threat and was also “engaged with our faith based partners in the affected community.” CNN has reached out to the FBI.

New Jersey Gov. Phil Murphy said he is in touch with the FBI, the state’s Office of Homeland Security and Preparedness and the state attorney general.

“We are closely monitoring the situation and are working with local law enforcement to ensure that all houses of worship are protected,” Murphy wrote on Twitter.

New Jersey Attorney General Matt Platkin said law enforcement will be increasing patrols in “sensitive areas” out of an abundance of caution and urged residents not to be alarmed if they notice an increased police presence.

“We also call upon New Jersey residents to be extra vigilant and if you see suspicious activity please report it to your local authorities without delay,” the attorney general said.

Advice from a security company
The president of a company that provides security for hundreds of Jewish houses of worship and schools in the New Jersey and New York area told CNN he sent out guidance to clients to ask for additional security from law enforcement.

Synagogues should contact local law enforcement and “request not just increased patrols but actual manpower during prayers and other activities,” said Joshua Gleis, of Gleis Security Consulting.

Gleis also advised synagogues not to conduct outdoor activities until further notice and to pull down exterior shades.

He also advised Jewish schools in the area should take similar actions until more information is available, as “any credible threat to a Jewish synagogue can become one to a Jewish school or community center.”

The NYPD also said Thursday its Intelligence and Counterterrorism Bureaus were working with the Joint Terrorism Task Force and the FBI to “ensure the safety and well-being of every area that encompasses our Jewish citizens and synagogues here in New York City and the tri-state area.”

New York Gov. Kathy Hochul clarified there was no related threat in New York but that officials were continuing to monitor the situation.

“Hatred, threats, or violence toward Jewish communities is unacceptable. We will always stand with our Jewish neighbors,” Hochul said on Twitter.

Antisemitic comments across the country
Over the past few years, the US has seen a rise in antisemitic incidents, with 941 incidents in 2015 jumping to 2,717 tracked in 2021 by the Anti-Defamation League. On Thursday, the ADL said it was working with the FBI to address the credible threat and advised synagogues and Jewish organizations to “remain calm and in heightened state of alert.”

The FBI’s warning on Thursday comes amid continued reports across the country of anti-Jewish bigotry, including multiple antisemitic messages that appeared in public spaces in Jacksonville, Florida, over the weekend, and a group of demonstrators who hung banners over a Los Angeles freeway earlier in October showing support for antisemitic comments that were made by Kanye West. Photos also showed the group with their arms raised in what appeared to be the Nazi salute. Los Angeles officials condemned the incident.

West previously made a series of antisemitic outbursts, notably on October 8, when he tweeted he was “going death con 3 [sic] On JEWISH PEOPLE,” and also that, “You guys have toyed with me and tried to black ball anyone whoever opposes your agenda,” without specifying what group he was addressing, according to the Internet Archive’s Wayback Machine records pulled by CNN.

His tweet was removed and Twitter locked his account. In an interview conducted after the controversial tweet, West told Piers Morgan that he was sorry for the people that he hurt but said he didn’t regret making the remark.

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