Fans invaded the pitch and there were reports of violence between rival supporters as Millwall took on Leicester City this weekend.
Millwall fans stormed the pitch after their team beat Leicester City 1-0 at the FA Cup tie on Saturday (February 18).
Two Leicester City fans and one Millwall fan were later arrested outside the stadium.
A Leicester City fan wrote on Twitter: "There were objects being launched into our supporting end.
"Few coins narrowly missing fans. No need."
Another Twitter user, Jason Mills, wrote: "There was a child no older than five giving obsene gestures, copying adults".
A spokeswoman for the Metropolitan Police said: "Officers dealt with disorder outside the stadium following the Millwall v Leicester City FA Cup tie on Saturday, 18 February.
"Three men were subsequently arrested on suspicion of affray.
"A 57-year-old Millwall fan arrested on suspicion of affray was released with no further action.
"A 49-year-old man and a 25-year-old man, both Leicester City fans, arrested on suspicion of affray both accepted a caution.
"No officers or police horses were injured. Enquiries continue."
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