Jeremy Corbyn is facing the biggest threat yet to his political leadership, with many members of the shadow cabinet resigning in the space of just a few hours, plunging the Labour Party into turmoil.
Here is a list of the shadow ministers who have resigned so far and why they went.
Shadow health secretary Heidi Alexander became the first of Corbyn's front bench to hand her resignation in.
She was elected MP for Lewisham East in 2010 having served as a local councillor in the borough for several years. She supported Andy Burnham for Labour leader but agreed to serve in Corbyn's shadow cabinet despite reportedly telling her activists that he is unelectable as prime minister.
In her resignation letter, she said it was "with a heavy heart" that she decided to stand down but she does not think Corbyn can lead Labour during Brexit negotiations.
She added: "As much as I respect you as a man of principle, I do not believe you have the capacity to shape the answers our country is demanding and I believe that if we are to form the next government, a change of leadership is essential."
Shadow Scottish secretary Ian Murray is the only Labour MP left in Scotland after the SNP's sweeping victories north of the border in the 2015 general election.
He was first elected to Westminster for Edinburgh South in 2010 having previously been a councillor. He has been critical of some of the language used by Corbyn's shadow chancellor and close ally John McDonnell, who he has accused of "ramping up rhetoric" against some centrist Labour MPs.
He said there is a "grave risk" Scotland could go for independence and the UK could break up in the wake of the Brexit vote and he feels Corbyn does not have the skills to lead the party during this tumultuous time.
In his resignation letter, he said: "With the result of the referendum on the European Union, the country faces a deeply challenging time ahead.
"That demands a strong opposition capable of holding the Government to account, helping to secure the best possible deal for Scotland and the UK and building to win any future general election. I do not believe that can be achieved under your leadership."
Shadow education secretary Lucy Powell has been the MP for Manchester Central since 2012. She was a key ally of Ed Miliband, helping to run his ill-fated general election campaign.
Resigning, she said the Labour Party faces an "existential threat" and warned that it has lost the support of many of its traditional voters.
She said: "Given the big challenges faced by our country and our party over the coming months, and the possibility of an imminent general election, I do not have the confidence that you can bring the party together, lead us to a general election and be an effective opposition."
Shadow transport secretary Lilian Greenwood, MP for Nottingham South since 2010, was first promoted to the Labour front bench by Ed Miliband and kept on by Corbyn.
She echoed the concerns of many of her former front bench colleagues that Brexit will cause economic hardship and be accompanied by growing intolerance.
She said: "Faced with such challenges, it is essential that we have a strong and united opposition. You are a kind, decent and principled colleague, but in my view a new leadership is required to bridge the widening divides in our party, both in Parliament and in the country as a whole."
Shadow environment secretary Kerry McCarthy was elected MP for Bristol East in 2005 having been selected as candidate in the first Labour all-women shortlist.
She has sparked several controversies on Twitter during her time as an MP. She apologised and received a police caution after revealing a sample of postal votes on Twitter during the run-up to the 2010 election. And in 2012 she branded a train passenger a "lager drinking oaf" and suggested he should have "been killed before he could breed" in an outburst on Twitter.
She told Corbyn: "The referendum result was a huge disappointment, and we now face the challenge of negotiating our future relationship with the rest of Europe. Vital protections won through our EU membership must not be jettisoned.
"This requires strong leadership from the Labour Party, and an alternative vision for government, which is seen as credible by the wider electorate. Although I do not doubt your personal commitment to your long-held principles, I believe that a new leader is needed to take on the challenges ahead."
Shadow minister for young people Gloria De Piero is a former journalist who became the MP for Ashfield in 2010.
According to The Guardian, she told Corbyn in her resignation letter: "I do not believe you can deliver that victory at a general election, which may take place in a matter of months.
"I have been contacted by many of my members this weekend and it is clear that a good number of them share that view and have lost faith in your leadership."
Shadow chief secretary to the Treasury Seema Malhotra is far closer to the Labour leader than the other rebels.
She was last seen with him on Saturday when she enthusiastically helped to introduce the Labour leader as he made his first public speech following the EU referendum vote.
But the MP for Feltham and Heston has joined a growing number of her Labour front bench colleagues in resigning.