The Jewish community must "redouble efforts to defend our community" and unite against hatred, religious and political leaders said at a vigil on Monday night for those killed in the Pittsburgh Tree of Life synagogue.

In a service held at the JW3 Jewish community centre in North West London, the President of the Board of Deputies, the Chief Rabbi, the Mayor of London and the Home Secretary addressed a crowd of more than 200, with many more watching via livestream video broadcast.

Candles were lit in the memory of the 11 congregants, who were murdered by a far-right gunman during Shabbat morning services on Saturday.

Board President Marie van der Zyl said that the fact the shouted "all these Jews have to die" as he entered the synagogue “chilled me to the bone".

“What has become clear is that this was not just an attack on Pittsburgh’s Jews, but on all of us," she said.

"We have no choice but to make this a call for action. We must redouble our efforts to defend our community… and we must continue to live proud Jewish lives.

“This weekend, I encourage all of you to show up for Shabbat and attend Synagogues to show our defiance and pride.

"We cannot take away the pain of this attack, but we can honour the memories of those who have had their lives so brutally taken, by fighting for a better future."

Chief Rabbi Ephraim Mirvis echoed the call, saying: “Let’s all go to Shul next Shabbos. Let every Jew around the world show, nothing will keep us away from standing with pride in our synagogues, praying to God as free Jews.”

He also spoke of the “eleven precious lives that were brutally taken from us… as two twin boys were about to enter the covenant of Abraham.”

He added: “It has been recognised that when Jewish blood is spilt in Pittsburgh, a shiver goes down the spine of every Jew around the world, but not just every Jew, but every caring person around the world.”

London Mayor Sadiq Khan described how “history is a guide to the dangers of allowing this hatred and prejudice towards the Jewish people to fester. It teaches us that whenever and wherever it rears its ugly head, it must be confronted, tackled and defeated. Because the consequences of indifference have been, and always will be, devastating.”

Home Secretary Sajid Javid said: “We often talk about the need to learn from history, but increasingly the present is echoing the worst of the past."

“We know that antisemitism doesn’t come out of a vacuum. People aren’t born with conspiracies and prejudices in their minds. This tragedy comes after antisemitic incidents in the US increased by a shocking 60 percent last year."

He sought to reassure the audience that police said the Pittsburgh attack "did not change the nature of the threat picture here in the UK".

But he added: “It is deeply shocking to me that there is so much anxiety from a longstanding and valued community in the UK. We are listening, we hear your concerns. We are proud to support the CST in protecting Jewish schools and synagogues, and as I said today in Parliament, we will also be open to looking at new ways of offering support.”

Rabbi Jonathan Wittenberg, senior rabbi of Masorti Judaism, described the Tree Of Life synagogue as “a sister community – a Masorti conservative community.

“Like them, my synagogue has a sign – ‘refugees welcome’.”

Before the attack, Bowers wrote on social media attacking HIAS, a Jewish charity that resettles refugees whose work the Tree of Life synagogue supported.

Rabbi Wittenberg also paid tribute to the eight men and three women who were killed, saying: “These people, none of them under fifty, are the kind of group which makes any service in a synagogue happen. The elders of the community, those who are always there. The faithful.”

Jessica Weinberg Neiss, a Pittsburgh native who recently moved to London, grew up in the Tree of Life synagogue, telling those at the vigil: “My little part of the world was absolutely torn apart this Saturday.

"Not only was Tree of Life in my neighbourhood, it was part of my home. I grew up in that Shul, I was batmitzvah’d there, I went to Sunday and Hebrew school there.

“The awful man who murdered eleven people in the building that I know and love – my home has been violated. He has ripped open and defiled my sacred space, and it will never be the same again.”

She said she knew three of the victims but added: “Whether or not I knew the victims is a moot point... What matters is that those victims could have been you or me.

"They were Jews, and they were only murdered because they were Jewish. That awful man saw all Jews as the enemy. And that is why now more than ever before we must unite as Jews. We need to stand up to all hatred and antisemitism.”

Fiyaz Mughal, the founder and director of the Tell MAMA Islamophobia watchdog, told the audience: “You are not alone in this fight against extremism....

"We stand with you to defend the very values that are the beating heart of your community.

“Time and time again, the very beating heart and essence of Judaism shows itself by the care, attention and affection it provides to other communities.

“This is what this community tried to do. They stood up, as Jews, for refugees. And they were murdered for being Jews because they cared about people that looked like me.”

Other speakers included US ambassador Woody Johnson, Israeli ambassador Mark Regev, Hannah Rose, president of the Union of Jewish Students, Rabbi Laura Janner Klausner, senior rabbi of Reform Judaism and Rabbi Danny Rich, senior rabbi of Liberal Judaism.

Community Security Trust chief executive David Delew described the Pittsburgh attack as “one of our worst fears" and urged "everyone both inside and outside the Jewish community, to recognise that they have a role in the security efforts”.

At the end of the vigil, JW3 chief executive Raymond Simonson said: “Like many of you, I’ve spent my life walking in and out of Jewish community building, walking past volunteers and professionals, who maybe for part of my life I didn’t really pay much attention to, but who were there for a reason that sadly we have been reminded of so strongly today.

“Please make sure when you leave this building tonight, when you see those people standing out in the freezing cold this evening, you just thank them.

"Because they do this, week in, week out, all over the country, and the vast majority of them are volunteers.”