Labour Party members on email will have received a message from party Leader RtHon Jeremy Corbyn MP letting them know about the online book of condolences where they can leave messages.
In his message Jeremy said "Jo Cox was an outstanding and inspiring new Member of Parliament, who had already shown in her life and work her dedication to the cause of peace and social justice. She was killed doing the job she was elected to do — representing the people she was elected to serve, doing her duty to the public and our democracy.
"We have requested, and been granted, the recall of Parliament on Monday. The gravity of what has happened means that I have decided, in consultation with our Deputy Leader Tom Watson, and our General Secretary Iain McNicol, to suspend Labour's national referendum campaign this weekend. I have also asked that local campaigning is suspended until Sunday.
"Ours is a country where tolerance and respect for other people and different viewpoints have always been highly valued. Jo Cox stood for tolerance, justice, peace and human rights. We must come together as a country and face down hatred and intolerance in our society. We send Jo's family, her two young children and her husband Brendan our deepest condolences and love. They are in the hearts of all of us.
"Today we have established an online book of condolences so that Labour members and supporters can send their own messages of condolence and express their thoughts at this troubling time. I hope this will help us all to come together in solidarity and in dedication to a better world."
You can add your message here: http://www.labour.org.uk/jo-cox