Jewish centers and schools across the nation coped with another wave of bomb threats Monday as officials in Philadelphia made plans to repair and restore hundreds of vandalized headstones at a Jewish cemetery.


Jewish Community Centers and day schools in at least a dozen states received threats, according to the JCC Association of North America. No bombs were found. All 21 buildings — 13 community centers and eight schools — were cleared by Monday afternoon and had resumed normal operations, the association said.


It was the fifth round of bomb threats against Jewish institutions since January, prompting outrage and exasperation among Jewish leaders as well as calls for an aggressive federal response to put a stop to it.


In Cherry Hill, New Jersey, a Jewish Community Center was evacuated Monday morning after a threatening call, CBS News’ Jeff Pegues reported. Since the beginning of the year, there have been at least 90 similar phone calls across 30 states and one Canadian province.


A U.S. official says the calls appear to be coordinated. Some may be originating from overseas. They range from individuals phoning in threats to machine-generated or altered calls.


The phone threats have targeted Jewish Community Centers in waves from East to West coast. They usually come around late morning when centers are in full use, Pegues reported.


“The Justice Department, Homeland Security, the FBI, and the White House, alongside Congress and local officials, must speak out — and speak out forcefully — against this scourge of anti-Semitism impacting communities across the country,” said David Posner, an official with JCC Association of North America. “Members of our community must see swift and concerted action from federal officials to identify and capture the perpetrator or perpetrators who are trying to instill anxiety and fear in our communities.”


The FBI and the Justice Department’s Civil Rights Division are probing the threats.


Attorney General Jeff Sessions called the vandalism and bomb threats serious, unacceptable behavior and said the department will “do what it can to assist in pushing back … and prosecuting anybody that we can prove to be a part of it.”


“We are a nation that is a diverse constituency, and we don’t need these kind of activities,” Sessions said.