Thousands attended a memorial service for the victims of Pittsburgh’s Tree of Life*Or L’Simcha Synagogue on Sunday night, where many decried the growing toxic political discourse in the United States, while vowing to come together to embrace tolerance and unity.

Tree of Life Rabbi Jeffrey Myers, who was leading prayers when the shooter opened fire, told political leaders that they must put an end to hate speech.

“My words are not intended as political,” said Myers. “My mother always taught me that if you don’t have anything nice to say, don’t say it.”

Rabbi Jonathan Perlman, who heads the New Light congregation, one of the other denominations that uses the Tree of Life synagogue, vowed that the shooting “will not break us, will not ruin us.”

“We will continue to thrive and sing and worship and learn together and continue our historic legacy in the city with the friendliest people that I know.”

The service, held at the University of Pittsburgh’s Soldiers and Sailors Hall, included more than 4,000 attendees from across the Jewish and non-Jewish communities in Pittsburgh, including the Gov. Tom Wolf, Mayor Bill Peduto, the state’s congressional delegation, as well as U.S. President Donald Trump’s Special Envoy Jason Greenblatt, Israeli Ambassador Ron Dermer and New York Israel Consul General Danny Dayan.

The service also included clergy from other faiths, including Christian and Muslim leaders, who briefly gave remarks.

Pittsburgh Mayor Bill Peduto said during the service that the incident was the “darkest hour” in his city’s history.

“But here’s another thing about Pittsburgh. We are resilient. We will work together as one. We will defeat hate with love. We will be a city of compassion and we will be welcoming to all people,” he said to cheers.

Israel Minister of Diaspora Affairs Naftali Bennett flew in from Israel to attend the service on Sunday.

“Our whole nation is feeling the pain you are feeling here after this heinous hate crime. I want to extend my condolences to the families of the victims,” said Bennett.

He added that “people who have seen so much in their lives could not imagine they would be gunned down in Shabbat prayer.”