Police in England are investigating two allegations of assault after disruption during West Ham United's Premier League defeat at home to Burnley.
Some fans invaded the pitch at the London Stadium while others vented their anger at the board during their 3-0 reverse, causing the game to be interrupted.
At one stage, Hammers veteran Mark Noble wrestled a supporter to the ground after he stormed on to the pitch and grasped a corner flag.
A Met Police spokeswoman said: "Towards the end of the fixture between West Ham and Burnley at the London Stadium on Saturday, four separate pitch invasions by individual home fans took place.
"During the pitch incursions an impromptu protest took place within the stadium with around 200 people gathering under the Director's Box.
"Two allegations of assault have been received by police. These are being investigated.
"Exit from the stadium following the game passed without incident.
"At this stage there have been no arrests."
During the game, joint owners David Gold and David Sullivan, whose decision to uproot the club from its Upton Park ground to the former Olympic Stadium is behind the anger, are understood to have left their seats for their own safety.
In a statement, the club said: "West Ham United have immediately launched a full and thorough investigation into the incidents which marred the second half of today's match and are committed to taking decisive and appropriate action.
"An emergency meeting has been called with all London Stadium stakeholders. There will be no further comment at this time."