West Ham have vowed to help the investigation into the shocking scenes of violence last night at Upton Park but could also face action themselves.
The Football Association are looking into the events surrounding the 3-1 Carling Cup defeat of Millwall that saw a man stabbed outside the ground and pitch invasions following West Ham's goals.
"West Ham will fully investigate the deplorable scenes that took place during the Carling Cup tie with Millwall on Tuesday evening," West Ham's statement read.
"The club will not tolerate the unacceptable behaviour witnessed inside the Boleyn Ground and will take the strongest possible action against anyone found responsible, including life bans.
"As was the case before, during and after the match, we are co-operating fully with the relevant agencies, including the police."
The club, however, could still be punished for the pitch invasions.
An FA spokesman said: "We absolutely condemn all of the disorder that has occurred at Upton Park, both inside and outside the ground. We will be working with all parties including the police and clubs to establish the facts surrounding the events.
"We expect all culprits to be banned from football for life. They have no place in our game."
Hammers boss Gianfranco Zola described his shock after the ugly clashes.
Neil Harris had given the visitors the lead but Junior Stanislas' equaliser that sent the tie into extra-time led to supporters pouring over the advertising hoardings.
Stanislas may not have helped the situation by celebrating in front of the Millwall fans. He added another from the penalty spot, leading to another invasion and Millwall players heading for the dressing room, before play got under way again and Zavon Hines added a third to seal victory.
"I've been involved in difficult games and things happened. Here, I've played seven years and I've never seen it like this," Zola said.
"It's certainly not good for football. I was completely shocked. Totally. I knew it was a game that meant a lot for the two sets of supporters, but I didn't imagine it like this.
"What can I say? I'm a sport man. I love the game. I love to go on the pitch and try and make it exciting for the supporters and enjoyable for everybody to watch. This was beyond my powers."
Carlton Cole was the victim of monkey chants, before the England striker appeared to make a gesture back to Millwall fans.
"I didn't know he was abused by the supporters," Zola said.
Instead of the talk being of Jack Collison bravely declaring himself ready to play despite his father dying in a motorcycle accident on Sunday, there were concerns at kick-off about the trouble that led to a tube delay and empty seats.
Of Collison's situation, Zola added: "He showed what kind of boy he is by playing. Not many would have done the same thing."
Millwall boss Kenny Jackett said of the ugly scenes: "I didn't fear for my own safety. There were no Millwall fans on the pitch. They stayed where they were supposed to.
"There were a lot of people on the pitch. The lads gathered together and came to the sides, as they should have."
He added: "I wasn't aware of the stabbing outside the ground. I'm very sad to hear that. We've got a passionate game in this country but when it oversteps the mark then things have to be done."