The international organization of Conservative rabbis on Sunday dismissed U.S. President Donald Trump’s claim that beefed-up security at the Pittsburgh congregation affiliated with their movement could have prevented the massacre.

At least 11 worshippers at the Tree of Life congregation in the Squirrel Hill neighborhood were shot dead by a gunman identified as Robert Bowers in what is believed to be the worst attack in history against the American Jewish community.

"This is a case where, if they had an armed guard inside, they might have been able to stop him immediately," Trump told reporters on Saturday. "Maybe there would have been nobody killed, except for him, frankly. So it's a very, very - a very difficult situation."

“Mass shootings have become a far too common occurrence in the United States,” the Rabbinical Assembly of the Conservative movement said in a statement issued after Shabbat let out. “Calls for extra security can only accomplish so much when so little is being done to screen gun purchasers and limit the lethality of weapons for sale.”

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The Tree of Life congregation is affiliated with the Conservative movement. An estimated 18 percent of American Jews belong to this movement.

According to the statement, Rabbi Jeffrey Meyers, the spiritual leader of the Pittsburgh congregation, is a member of the Conservative movement’s Cantors’ Assembly.

Describing themselves as “reeling in the wake of this tragedy,” the rabbinical leaders noted that “one of the most important lessons that the Jewish people can teach the world is that an act of hate against one community is an act of hate against us all.”

Open gallery view People hold candles as they gather for a vigil in the aftermath of a deadly shooting at the Tree of Life Congregation, in the Squirrel Hill neighborhood of Pittsburgh, Oct. 27, 2018. Credit: AP Photo/Matt Rourke

“This mass murder is a reminder that anti-Semitism is on the rise in America at a rate unprecedented in decades,” they wrote. “This vicious hate crime, perpetrated against innocent people at prayer is but the latest in an escalating scourge of hate-based violence in America.”

The statement said that “it is not lost on us” that the congregation was singled out for participating last week in a HIAS event that was meant to welcome refugees into the United States. It noted that “hundreds of synagogues led by our rabbis have participated.”

The Conference of Presidents of Major Jewish Organizations said its members were “saddened as we are outraged” by the murderous attack.

“This hate-driven murderous assault on innocent people attending a religious service must be condemned by all people who care about our society and country,” it said in a statement. “But words are not enough. There must be concrete action at every level to address the promoters of hate and the sources of incitement to violence if we are to root out racism, bigotry and anti-Semitism, which have increased significantly in recent years. There must be zero tolerance for intolerance. No excuses no exceptions.”

The statement described as “noteworthy” the fact that the incident coincided with the 80th anniversary of Kristallnacht [“night of broken glass"] in Germany – an event considered to have been the harbinger of the Holocaust. “While there is no comparison between the apparent act of an individual and state-organized actions,” it said, “it is a reminder that we must act decisively and immediately to prevent the cancer of anti-Semitism from growing and infecting our society.”

AIPAC, the pro-Israel lobby in Washington, said that “sadly, today's slaughter does not stand alone as representing the scourge of anti-Semitism. Throughout the world, we are witnessing the alarming rise of hatred directed against Jews and Jewish institutions.”