Crowd trouble marred West Ham’s EFL Cup fourth-round home win over Chelsea, with police making seven arrests.
Plastic bottles, seats and coins were thrown during the Hammers’ 2-1 victory at London Stadium as hundreds of supporters clashed and riot police entered the concourse.
It is the latest outbreak of disorder at West Ham’s new ground this season.
West Ham boss Slaven Bilic called the behaviour “unacceptable”, adding: “We are totally against it as a club.”
The club says it will ban any fans involved for life.
Until Wednesday’s match, the Metropolitan Police have not deployed officers inside the stadium because the radio system emergency services use to communicate will not be operational until 2017.
This season, the Hammers’ first at the former Olympic Stadium following their move from Upton Park, 23 fans have been banned from the ground.
Four people were arrested following disorder at the Premier League match against Middlesbrough on 1 October, while there were clashes in the stands during the defeat by Watford in September.
The Metropolitan Police, who made seven arrests for alleged public order offences, described Wednesday’s incidents as “unacceptable” and said 30 people were prevented from attending the match.
It said part of its investigation will include “a leaflet handed out before the match containing homophobic contents”.
Images on social media before the game appeared to show a song sheet being distributed with homophobic lyrics aimed at Chelsea defender John Terry and striker Diego Costa.
‘Someone will get killed there’
Bilic added: “For those kind of things to happen, especially in England, is unacceptable.”
Chelsea manager Antonio Conte said: “I don’t really like to see these situations.”
One fan at the game told BBC Radio 5 live it “was an absolute nightmare”, adding: “If they don’t close that stadium someone will get killed there.”
West Ham said in a statement they “unreservedly condemn” fans’ behaviour and will work to identify those supporters involved, while Chelsea said they were “extremely disappointed to see disturbances”.
Police commander BJ Harrington said: “There were a minority of people who attended the match that were clearly intent on being involved in confrontation and violence.
“Despite extensive work with both clubs and a large and robust policing operation, there were unacceptable incidents inside and outside the stadium, before, during and after the game.”