In the build up to, and during, the West Ham/Millwall match violence took hold in and around Upton Park.
One man was stabbed in the chest, and a BBC reporter has heard that a second stabbing has occured. Another fan said that his father had to receive medical attention after having a dart thrown at his head. There have been five confirmed arrests so far.
The Metropolitan police say that the hooliganism is likely to have been organised beforehand.
These events have been responsible for interruptions to the play; riled fans invaded the pitch a number of times resulting in the players being taken off.
This is all after West Ham player, Calum Davenport, was stabbed earlier in the week whilst staying with his mother.
Update: Fans are being told to stay in ground whilst fighting continues outside