The editors of the Daily Mirror and Sunday Mirror have both left with "immediate effect" as the paper moves toward a seven-day operation.
Daily Mirror editor Richard Wallace, and Sunday Mirror editor Tina Weaver both left their positions on Wednesday morning.
The company said in a statement: "The roles of editor Daily Mirror and editor Sunday Mirror have been made redundant and therefore Richard Wallace and Tina Weaver will leave the company with immediate effect.
"Both Richard and Tina leave with our best wishes for the future and our thanks for the extremely valuable contribution they have made to the Daily Mirror and Sunday Mirror during their tenure as respective editors."
Sources described the moment Wallace, who has edited the paper since 2004, reacted as the email was sent around the building, telling staff he was shocked.
As the former editor walked out of the newsroom, he was clapped out by the whole office.
Lloyd Embley, the current editor of The People, will edit the new seven-day paper.
The Mirror's statement added: "The seven day organisation across the two titles is enabled through the company’s multi-million pound investment in the ContentWatch editorial system.
“The new structure will ensure that our newsroom is fully equipped to achieve the company’s multi-media publishing strategy across our newspapers, online, mobile and new e-editions for tablet devices.”
According to sources at the paper, Embley gave a rallying speech to the newsroom following Wallace's departure. Staff are said to be nonplussed after Wednesday morning's events.
The 46-year-old was described an approachable, competent editor who was teased for being posh and wearing flat caps, by former colleagues from the Mirror.
One said, however, "he's not exactly from the same background as Daily Mirror readers."
Wallace was the Sunday Mirror's deputy editor until taking the top job at the Daily Mirror in 2004, having worked as a showbiz reporter at the paper previously.
He replaced Piers Morgan at the helm of the daily tabloid when Mr Morgan was dismissed after publishing photographs - later shown to be fakes - which purported to show British soldiers abusing Iraqi prisoners.
Weaver became editor at the Sunday Mirror in 2001 after working her way up as a reporter on the now defunct Today and the Daily Mirror.
Trinity Mirror group chief executive Sly Bailey is also stepping down, and is expected to leave by the end of the year.
The moves came after the group, which publishes the Daily Mirror, Sunday Mirror and 160 local and regional newspapers, prepares to face down a potential revolt over executive pay at its annual meeting next week.
Media commentator Roy Greenslade questioned if the sacking were Bailey's revenge, writing:
"Their sackings came as a shock to them and their staff this morning. They were called in by Mark Hollinshead, Bailey's lieutenant, to be given their marching orders."
Michelle Stanistreet, the general secretary of the National Union of Journalists (NUJ), said the move was "brutal" and "an example of a company in crisis".
She said: "It says a lot about the board of Trinity Mirror that they have allowed chief executive Sly Bailey, finally on her way out after presiding over stupendous decline, to push such drastic measures through. The statement from the company tries to dress up this last hurrah as a leap into a brave new world of multimedia publishing - the reality is that these cuts and the weakening of the titles' identities will be a further blow to resources and quality journalism from a lame duck chief executive whose monumental lack of vision has seen the company's fortunes plummet."
The company's full statement can be read below:
Trinity Mirror announces today that the Daily Mirror and Sunday Mirror are to move to a seven day publishing model.
The decision, approved by the Board, is a further step towards creating one of the most technologically advanced and operationally efficient newsrooms in Europe.
The seven day organisation across the two titles is enabled through the company’s multi-million pound investment in the ContentWatch editorial system. The new structure will ensure that our newsroom is fully equipped to achieve the company’s multi-media publishing strategy across our newspapers, online, mobile and new e-editions for tablet devices.
Lloyd Embley has been appointed Editor of the Daily Mirror and Sunday Mirror with immediate effect. Lloyd was previously Editor of The People and will continue to report to Mark Hollinshead, Managing Director Nationals.
Two new senior editorial roles have been created with an Editor for the Daily Mirror (weekdays) and a Weekend Editor of the Mirror which combines the editorship of the Daily Mirror on Saturday with that of the Sunday Mirror. Both roles will report to Lloyd Embley. These appointments, together with a new Editor for The People, will be announced imminently.
In addition Paula Scott has been appointed Publishing Director Magazines and will continue to report to Mark Hollinshead, Managing Director, Nationals. Paula was previously Business Development Director.
As a consequence of these changes the roles of Editor Daily Mirror and Editor Sunday Mirror have been made redundant and therefore Richard Wallace and Tina Weaver will leave the company with immediate effect.
Mark Hollinshead, Managing Director Nationals said: ‘At the core of our business the Daily Mirror is as strong as ever with year on year circulation trends, despite widespread cut price competition, out performing the market in 11 out of the last 12 months.
‘Today’s announcement represents an important step change in meeting the needs of a multi-media publishing environment. The next 12 months will be transformational for our business as we continue to grow our online audience, maximise audience delivery on mobile and launch new e-editions for tablet devices in addition to further developing our newspapers.
‘I’m delighted to appoint Lloyd to the position of Editor of the Daily and Sunday Mirror. He is an accomplished editor who has done a first class job on improving the performance and profile of The People having spent several years on the Daily Mirror in a senior executive role.
‘Both Richard and Tina leave with our best wishes for the future and our thanks for the extremely valuable contribution they have made to the Daily Mirror and Sunday Mirror during their tenure as respective Editors.’
See below for a slideshow of reaction