On Monday, 11 Jewish Community Centers (JCCs) received phoned-in bomb threats, causing evacuation of the facilities, some of which included fitness centers, according to the JCC Association of North America, New York. The threats were determined to be hoaxes, and no one was harmed.

The latest threats occurred after three waves of bomb threats in January (Jan. 9, Jan. 18, and Jan. 31). As of Feb. 21, 69 threats have occurred at 54 JCCs in 27 states and one Canadian province, according to the JCC Association of North America. All of the earlier bomb threats also proved to be hoaxes, and all JCCs impacted have returned to regular operations but with a heightened level of security, according to a statement by David Posner, director of strategic performance at the JCC Association of North America. Among other consulting services, the JCC Association advises local JCCs on security policies and practices.

"Our centers have in place security protocols to ensure the safety of their program participants and facility visitors," Posner said in the statement. "As always, safety is our top priority, and we are continuously impressed with the JCC professionals on the ground who are relying on established best practices and strong relationships with law enforcement agencies to ensure the wellbeing of all who use and benefit from their facilities. Our JCCs are strongly rooted in communities across the country, and we will not be cowed by threats intended to disrupt people's lives or the vital role Jewish community centers play as gathering places, schools, camps, and fitness and recreation centers."

The JCC Association is coordinating updated security trainings for JCC executives and staff, he said. The JCC Association partners with Secure Community Network, which was established after the Sept. 11, 2001, terrorist attacks to focus on security for Jewish institutions throughout North America, as it develops action plans and provides guidance, recognized practices, and research to local JCCs.

The JCC Association is concerned about the anti-Semitism behind the threats, and the repetition of threats intended to interfere with day-to-day life.

"Local JCCs serve not just the Jewish community, but the entire community," he said. "Participants from all different backgrounds come to their local JCCs for activities, Jewish cultural and religious programming, and opportunities to come together as a community."

The JCC Association is in regular communication with the FBI, which is investigating the threats, he said.

A full list of JCCs, which have confirmed receiving bomb threats over the course of the four dates, can be found online.

Despite the fact that none of the threats proved real, JCCs have faced violence in the past. One of the most recent cases involved shootings at a JCC in Overland Park, Kansas, in April 2014 in which Frazier Glenn Cross, a man who had expressed anti-Semitic views, shot and killed two people. He then drove to a nearby Jewish retirement home and shot and killed one other person. In September 2015, he was convicted of the killings and given the death penalty.