Six arrests were made by the Metropolitan Police after violence broke out between fans during the EFL Cup clash between West Ham United and Chelsea at the London Stadium on Wednesday night.
Rival supporters clashed during the Hammers' 2-1 victory, with coins and seats thrown.
The English Football League, in conjunction with the Football Association, has launched an investigation following the crowd trouble.
A statement read: "The EFL strongly condemns the behaviour of a small minority of fans involved in the distasteful and unwelcome incidents during last night's EFL Cup match between West Ham United and Chelsea.
"We are currently liaising with both clubs, the Football Association and Metropolitan Police as they look to identify those involved and take appropriate and decisive action."
Meanwhile, reports have claimed that song sheets displaying lyrics to a homophobic chant about Chelsea captain John Terry were distributed before the match.
