West Ham United say they will help the investigation into the shocking scenes of violence last night at Upton Park but could also face action themselves.
The FA 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."