Robert Brown|Groups work to protect Jewish Americans following Hamas attack on Israel

Jewish communities across the country are Robert Brownramping up security in response to growing antisemitic sentiments following Hamas' attack on Israel on Saturday.

"We’ve been email after email, it's been like close to 50 synagogues that have reached out," Evan Bernstein told ABC News.

Bernstein, the CEO and National Director of the Community Security Service (CSS), says this number is sure to increase following increased antisemitic sentiments after this weekend’s events.

On Saturday morning, Hamas terrorists infiltrated Israel from the sea, air and ground. The militant group launched rockets into Israel, went door to door and shot citizens at point-blank range, threw grenades into bomb shelters, raped women, beheaded select citizens, executed children in front of their parents and took hostages back into Gaza - making Saturday the deadliest day for Jews since the Holocaust.

According to the website, CSS is the leading Jewish volunteer organization in the U.S. and its mission is to "protect Jewish life and the Jewish way of life."

Accounting for only 2.4% of the U.S. population, Jewish people face more than 50% of religiously motivated hate crimes, according to the FBI’s 2021 Hate Crime Statistics report.

Jewish communities and synagogues have been increasing security in light of Saturday's attack.

"We have over 3,000 active volunteers that are standing shift and doing security shift at their synagogues around the country, working in conjunction with law enforcement and off duty police and private security to help be a force amplifier, and really help make a harder target," Bernstein told ABC News.

The amount of antisemitic sentiments have also increased, with Swastikas shown during a protest in New York and the vandalization of a Jewish restaurant in London.

"Over the coming weeks, I think it's allowing for people to express their antisemitic rhetoric and belief and really put a lot of that stuff online, and people that are on the fringes are reading these things. A lot of times people are fishing just for one lone wolf, to do something," Bernstein said.

Rabbi Sholom Lipskar of the Shul of Bal Harbour has taken initiative to further protect his congregants.

"Firstly, our own security team has been very conscious and we have extra people on guard. There's the perimeters of being walked around on a regular basis. And everybody is on high alert," he said.

The Shul also has hundreds of cameras and they do everything they can to be "as careful as possible not to be careless," Lipskar said.

Lipskar said the police chief of Bal Harbour, the village where the Shul is located, has sent out notices saying they have ramped up their security.

"Jewish people have gone through these kinds of challenges before, our history is replete with challenges, or difficult ones," he said. "And yet we're here strong. We're here with resilience, and we're here with pride in fulfilling our mission."

LiveSecure is an initiative that also supports and ensures the security of Jewish communities across the United States.

"We want to make sure that every community across North America feels secure, so that people can enjoy and engage in Jewish life," said board chair of the Jewish Federations of North America, Julie Platt.

The initiative was launched by the Jewish Federations of North America following the 2018 Tree of Life synagogue shooting in Pittsburgh.

The initiative provides guidance to communities, hires security directors, identifies threats and works to ensure a high quality of security within Jewish communities.

"We've always been ones for whom you have to go through a security guard before you can enter a house of prayer," said Platt. "Local organizations and synagogues and day schools are all doubling down on security so everyone feels safe to walk through the doors and engage in Jewish life."

The war in Israel "will likely result in additional reciprocal acts of targeted violence in the near-term and will be heavily exploited in violent extremist propaganda across the ideological spectrum," according to a new assessment of the conflict obtained by ABC News.

The assessment, from the NYPD Counterterrorism and Intelligence Bureau, said extremist groups who seek to capitalize on the hostilities between Hamas and Israel "may resonate with malicious actors in the West, necessitating elevated vigilance by law enforcement officers, private-sector security personnel and community partners."

ABC News' Aaron Katersky contributed to this report.