Slaven Bilic has been sacked as West Ham manager with the team in the Premier League relegation zone.
Bilic’s last game in charge was Saturday’s 4-1 defeat by Liverpool at London Stadium.
A statement from West Ham said the club believed a change was necessary “to move forward positively and in line with their ambition.”
Former Everton and Manchester United boss David Moyes has been strongly linked with succeeding Bilic.
West Ham say Bilic’s coaching assistants Nikola Jurcevic, Edin Terzic, Julian Dicks and Miljenko Rak have also left the club with immediate effect.
Chris Woods, who was goalkeeping coach under Moyes at Everton and United, is the only member of the coaching staff to remain.
“The club’s search for a new manager to take West Ham United forward is under way and an announcement regarding Bilic’s successor is expected to be made over the coming days,”
Former Croatia defender Bilic, 49, was appointed in the summer of 2015 and guided West Ham to seventh place in his first season in charge.
But an 11th-placed finish last term, their first at London Stadium, has been followed by a poor start this season.
The Hammers have won just two Premier League matches in 2017-18 – and lost their first three league matches of the campaign.
Speaking after the defeat by Liverpool, Bilic told BBC Sport: “The pressure mounts game by game and at this moment it is big.
“I don’t feel a broken man. On the other hand, the situation for West Ham is not good and the club is above every individual.
“I cannot say anything negative [about the owners]. They have been supportive, very good to me in my two and a half seasons, but the situation is very difficult.”
West Ham’s next match is at Watford on Sunday, 19 November.
Bilic – a success or a failure?
Bilic – who previously managed his country for six years – spent a reported £42m on players in the summer. That included the signings of forward Marko Arnautovic from Stoke City for a club record £20m, and former Manchester United striker Javier Hernandez from Bayer Leverkusen for £16m.
However, his side have taken just nine points from 11 league matches, conceding 23 goals in the process.
They endured a poor start to last season, too, winning just two of the first seven Premier League home games after moving into London Stadium, and suffering heavy defeats by Watford (4-2), Southampton (3-0) and Arsenal (5-1).
However, Bilic eventually guided the club to a mid-table finish and his record compares favourably with his predecessors, with none having claimed more Premier League points per game.