West Ham boss Slaven Bilic has condemned the supporters who clashed with visiting Chelsea fans, marring his side's EFL Cup win at the former Olympic Stadium.
Skirmishes broke out towards the end of the Hammers' impressive 2-1 fourth-round win as police and stewards battled to maintain segregation behind the goal being defended by West Ham.
Bilic, perhaps understandably, wished to focus on the fine performance of his team and was frustrated at facing questions about the "unacceptable" behaviour of a minority.
"I noticed it, of course," Bilic said. "The game was on. I was more concentrated (on the game).
"I don't know what happened. But whatever happened, we are totally against it as a club as a team.
"For those kind of things to happen, especially in England, is unacceptable."
Bilic was unhappy to have to address the violent scenes in his post-match media conference.
"Straight away, (for) the second question to be about something that I have nothing to say about is unfair towards the game," he said.
"Five minutes about the game and then we can talk about this.
"I think this game deserves to be talked about a little bit more.
"Ask me one question about the game. It was a London derby, 2-1 for us. Some great performances."
The Hammers boss had already spoken of a "great night for us", but the repercussions could be significant with the authorities sure to scrutinise the scenes.
Bilic added: "It's a great night for us. It was a great game of football, not only for us. It was a cup game, night game, packed stadium, London derby, against a team that hit great form recently, totally on fire.
"To put that kind of performance from us is really very important for us, not only for this competition but in general to gain more confidence in the team, individual and even more as a team.
"Of course to beat Chelsea you have to be on top of your game. We were."
This derby was billed as the biggest footballing test for the London Stadium so far, on a night when basketball and track cycling competitions were also taking place on the former Olympic Park.
The capacity is capped at 57,000 and 45,957 were in attendance, along with a heavy police presence.
Chelsea sold out their allocation of 5,182 tickets and, with the Hammers 2-0 up, trouble broke out.