Twenty-seven Jewish community centers (JCCs) across 17 U.S. states received bomb threats Wednesday, marking the second nationwide wave of threatening phone calls to such facilities in a 10-day span.

Sixteen American JCCs had received bomb threats Jan. 9. For Wednesday’s incidents, the community centers were “well-prepared” to handle the threats and swiftly engaged in security protocols, according to the JCC Association of North America umbrella organization.

The states in which JCCs received bomb threats Wednesday were Alabama, California, Connecticut, Delaware, Florida, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, New Jersey, New York, Ohio, Tennessee and Texas, the Anti-Defamation League (ADL) said.

“In the wake of last week’s calls, JCCs were well-prepared for the calls received today,” David Posner, director of strategic performance for the JCC Association, said in a statement. “Many JCC leaders took part in a webinar organized quickly by the JCC Association, featuring officials from SCN (the Secure Community Network) and the Department of Homeland Security to address concerns and procedures. Lessons learned and best practices discussed were clearly on display this morning, and we applaud our JCCs for responding calmly and efficiently.”

Posner, however, cautioned that the JCC Association is “concerned about the anti-Semitism behind these threats.”

“While the bombs in question are hoaxes, the calls are not,” he said. “We know that law enforcement at both the local and national level are continuing to investigate the ongoing situation. We are relieved that no one has been harmed and that JCCs continue to operate in a way that puts the safety of their staff, visitors and premises first.”

ADL CEO Jonathan A. Greenblatt expressed a similar sentiment, saying, “Although so far these threats do not appear to be credible, we are recommending that Jewish communal institutions review their security procedures and remain in close contact with law enforcement.”