On Monday, at least 30 Jewish community centers and day schools across 18 states received bomb threats that turned out to be false alarms, according to BuzzFeed News. The incident marks what Reuters and other outlets call the fifth wave of such anti-Semitic threats to take place in 2017. The previous wave happened just last week, when Jewish community centers in 11 states received bomb threats that were also found to be hoaxes.

States all over the U.S. were targeted during the most recent threats, including Florida, Alabama, New Jersey, New York, Delaware, Michigan, and California. There were no reports of any actual bombs being found or detonated, nor of any injuries, according to Vice News.

Shortly after the incidents, the Jewish Community Center Association of North America commented on the threats. "Anti-Semitism of this nature should not and must not be allowed to endure in our communities,” the JCCA's director of strategic performance, David Posner, said in a statement. “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."

The Anti-Defamation League, an organization that fights anti-Semitism and other forms of discrimination and bigotry, also received a bomb threat on Monday. “While this latest round of bomb threats to Jewish Community Centers and day schools across the country again appears to not be credible, we are nonetheless urging all Jewish institutions to review their procedures,” ADL CEO Jonathan A. Greenblatt said in a statement, according to Slate. “Since the start of 2017, we have witnessed nearly 90 bomb threats being called in to Jewish institutions, including one recently to ADL’s national headquarters.”

The bomb threats weren't the only anti-Semitic act to take place over the past few days. On Sunday, around 75 to 100 gravestones at the Jewish Mount Carmel Cemetery in Philadelphia were knocked over, according to BuzzFeed News. The crime is the second of its kind to take place in a week; the weekend before, around 100 gravestones at a Jewish cemetery in St. Louis were vandalized in similar fashion.

Vice News reported that there were no bomb threats against Jewish community centers in 2015, and only one incident in 2016 in that same time period. But while the threats are new, anti-Semitism in the U.S. isn't; data from the Federal Bureau of Investigation show that in 2015, anti-Semitic hate crimes were the largest group of religion-related hate incidents, followed by attacks against the Muslim community.

President Donald Trump hasn't spoken out about the latest wave of bomb threats, but he did offer a statement after the round of bomb threats that Jewish centers received last week, reported CNN. "The anti-Semitic threats targeting our Jewish community and community centers are horrible and are painful and a very sad reminder of the work that still must be done to root out hate and prejudice and evil," he said at the National Museum of African American History and Culture.

Steven Goldstein, the executive director of the Anne Frank Center for Mutual Respect, criticized Trump's statement, calling it a "Band-Aid on the cancer of anti-Semitism that has infected his own administration" in a Facebook post.

Related: Trump’s Answer to a Question About Anti-Semitism Involved Bragging About His Electoral College Win

Check this out: