Mrs Cox’s Jewish colleagues expressed sadness at the news. Luciana Berger, the Shadow Minister for Mental Health, tweeted: “Jo Cox was one of the best. A kind, wonderful, passionate, super talented colleague. My deepest condolences to Brendan and the family.”
Paying tribute to her human rights work, Labour MP Ivan Lewis, who is running for Manchester Mayor, tweeted: “Jo Cox changed the world for mums at risk of dying during childbirth and Syrian refugees. We pray for her family and must learn from her humanity.”
Isaac Herzog, Israel's Labour leader, tweeted: "I'm shocked to hear of the murder of British Labour MP Joe Cox. My thoughts, and those of all at Israel's Labour party, are with her family."
Jeremy Newmark, chair of the Jewish Labour Movement, knew both Mrs Cox and her husband Brendan socially.
He said he had come across Mr Cox, who worked in international aid and development, on projects looking to bridge relations between Jewish community institutions and NGOs like umbrella group Crisis Action.
Mr Newmark said: “She was a very human politician in every sense. She cared. She cared about issues and people.
“I knew and came across her at events through Brendan – they were informal and primarily social but inevitably our work came up in conversation.”
Levi Shapiro, who heads the strictly Orthodox JCC group, recalled meeting Mrs Cox. Mr Shapiro, from the Charedi community in Stamford Hill, said he lost his way around Parliament when she pointed him in the right direction.
He was on his way to an interfaith event, when he met her in April. He said: “She asked me if I needed help finding the room. I said yes.
“While we were walking, we got into a very friendly conversation and she showed a deep interest in why I had come. I went onto talk about the JCC and promoting young leadership. She told me: ‘We need young leaders’”.
UK Chief Rabbi Ephraim Mirvis paid tribute to Mrs Cox. He said: "We're united in grief today at the terrible loss of Jo Cox. Brutally murdered as she served constituents. May her memory be for a blessing."
Jonathan Arkush, president of the Board of Deputies, the representative body of British Jews, said: “We send our condolences and prayers to all of Jo Cox's family after her senseless and tragic murder.”
The Jewish Leadership Council tweeted: “The JLC is shocked and appalled at the senseless and tragic murder of Jo Cox MP. We send our sincere condolences to her husband and family.”
The Community Security Trust tweeted: "We are shocked and appalled at the attack on Jo Cox MP and our thoughts and prayers are with her and her family."
Yuli Edelstein, the speaker of the Knesset, said Israeli parliamentarians felt "deep shock and outrage" at the death of Mrs Cox.
In a letter to John Bercow, the Speaker of the House of Commons, Mr Edelstein wrote: "The repugnant and horrific murder of Jo Cox crosses a red line, a fact that a model society like Britain's must not accept. Such an incident must set off deafening alarms bells in any society that cherishes life, respects law and order, and abides by basic laws that grant people their human dignity and freedoms."
He expressed "deepest condolences to the Cox family, Parliament and the British people as a whole," adding: "We stand by you at your dire hour".
In a vigil after her death, Labour leader Jeremy Corbyn paid tribute to her work as a parliamentarian and human rights activist.
In a statement, Mr Corbyn said: “Jo was dedicated to getting us to live up to our promises to support the developing world and strengthen human rights.”
In the course of her career, she called for a resolution to the Israeli-Palestinian conflict and submitted a piece on the issue for Labour Friends of Palestine and the Middle East.
In her ‘Unlocking Gaza’a potential: beyond conflict and crisis’ article, she wrote: “The international community should prioritise efforts to stabilise and extend the current ceasefire, end the blockade to kickstart Gaza’s economy and allow greater freedom of movement both into and from Gaza.”
She called on her party to: “encourage the Israeli government to open up all crossings into and out of Gaza, and urgently allow free and unfettered access to Gaza for goods.”
She also said the Labour Party should “pledge to support a Palestinian national unity government, with Hamas and Fatah ministers, operating in both Gaza and the West Bank,” adding that it should also: “Press for an end to rocket or mortar attacks into Israel. Press for accountability for human rights abuses and violations of international law committed by all sides.”
After the attack, MPs were told to contact police to review their security arrangements.
