An overflow crowd was outside Adas Israel synagogue in Northwest Washington on Monday for an interfaith service to mourn the 11 Jews killed Saturday at Tree of Life synagogue in Pittsburgh. (Michael S. Williamson/The Washington Post)

The elected leaders of the District, Maryland and Virginia addressed an overflowing crowd of thousands of mourning Washingtonians on Monday night, as they decried the anti-Semitism that led to the killing of 11 Jews in Pittsburgh on Saturday.

At Adas Israel synagogue, D.C. Mayor Muriel E. Bowser (D), Maryland Gov. Larry Hogan (R) and Virginia Gov. Ralph Northam (D) joined Jewish congregants and clergy of many faiths in singing Jewish words of sorrow and resolve: “Help us find the courage to make our lives a blessing.”

The 1,400-seat sanctuary at one of the District’s largest congregations was filled to overflowing, and organizers of the memorial service said that 2,500 more people were watching on a live stream in as many rooms of the synagogue as possible.

The line stretched down the block; many more couldn’t fit in the building. Hundreds stood outside, where Rep. Jamie B. Raskin (D-Md.) spoke and people sang “Oseh shalom,” “make peace,” while the flashing blue lights of police cars lighted faces wet with tears.

Those inside sang, sobbed and listened to speeches both sermonic and angry by political leaders and leaders of the Jewish community.

“This past weekend, people in our nation were murdered in their house of worship, for who they are, for what they believe, for being Jews,” said Bowser, standing in front of 11 memorial candles, one for each person shot to death at Tree of Life synagogue in Pittsburgh. The accused gunman, Robert Bowers, is said to have shouted, “All Jews must die.”

To Washington’s Jews, Bowser said: “We love you, we mourn with you, and we are sorry that our society let you down on Saturday morning.”

Both governors drew upon traditional Jewish teachings in their remarks, hitting emotionally resonant chords for many in the sanctuary. Northam concluded with the customary words, “May their memories be a blessing.”

Hogan quoted Holocaust survivor and activist Elie Wiesel and spoke of the Hebrew prayer for mourners, the kaddish, which does not speak of death. “It serves of a reminder of the goodness in all of us that brings us together and makes us stronger, because in this battle between good and evil, there can be only one side to stand on,” he said.

While the politicians channeled their inner rabbi, it fell to a Jewish leader to give the most fiery political speech of the event.

“What is happening in our America? . . . Unfortunately, this was entirely predictable. Anti-Semitism, racism and bigotry have been normalized,” Jewish Community Relations Council of Greater Washington Executive Director Ron Halber said, crescendoing to a shout as he called for gun control and other policy solutions. “Something has become rotten in America’s moral fiber, in our society. And we must and we will take America back.”

When Halber declared that Jews will not be frightened out of their synagogues — “We will not cower!” — he prompted the first standing ovation of the night. The crowd stood again for a leader of HIAS, the Jewish agency whose work aiding refugees was cited by the alleged shooter, and when more than 100 clergy — half of them Jewish rabbis and cantors, half representing other faiths — crammed up front together for the recitation of the kaddish.

This type of service, Adas Israel’s Rabbi Lauren Holtzblatt reminded the participants, was the type that the victims killed at Tree of Life synagogue would likely have attended, and enriched. They were regular attendees of their synagogue who volunteered, led services and welcomed newcomers.

“They embodied the very best of who we are as Jews,” Holtzblatt said. “They are the ones who show up, always. You all know them, too. You may be one of them.”

The room full of those people, the faithful members of Jewish communities and their throngs of supporters, wept and embraced.

Sarah Kaplan and Lisa Bonos contributed to this report.