A number of Millwall fans broke through a police barrier and chased Barnsley supporters
Scuffles broke out at Wembley between fans at the League One play-off final between Millwall and Barnsley.
The police said there was an altercation between supporters at around 4.35pm, but no arrests have been made so far.
Trouble flared just moments before Barnsley secured promotion to the Championship, with a 3-1 win over the London side.
Millwall fans broke through police barrier and charging after Barnsley supporters pic.twitter.com/57u1EjBTh3— Football Away Days (@footyawayday) May 29, 2016
A spokesman said: "The Metropolitan Police Service will conduct a review and will liaise with the Football Association and the two clubs involved to identify those responsible and where necessary take the appropriate action."
Millwall said in a statement: "Millwall Football Club deplores the actions of a small minority of its fans during the second-half of Sunday's League One Play-Off Final.
"Such behaviour is unacceptable and anyone found guilty of disorder will face life bans from the football club."
The Football Association tweeted: "The FA condemns the disorder caused by a small number of fans at today’s League One Play Off final between Barnsley and Millwall.
"We will work closely with the clubs, the Football League and the Met Police to identify those involved and take appropriate action.
"We would like to take this opportunity to praise the actions of our stewards and the police, who responded responsibly under provocation."
There was also condemnation of the trouble by members of the public on social media.
The FA condemns the disorder caused by a small number of fans at today’s League One Play Off final between Barnsley and Millwall .— The FA (@FA) May 29, 2016