Six supporters were reportedly injured during the weekend's fierce Manchester derby, which was overshadowed by off-field incidents.
Manchester United managed to secure a late 3-2 victory over Manchester City at the Etihad Stadium on Sunday. However, the headlines were dominated by an incident which resulted in United defender Rio Ferdinand getting hit just above the eye with an object thrown from the crowd and being confronted by an angry pitch invader towards the end of the match.
It is understood that six fans were also treated for injuries relating to coin-throwing occurrences and a female police officer was punched in the face, according to the Manchester Evening News.
Superintendent Craig Thompson said: "Tensions were high and a late goal always makes things more difficult. But the behaviour of some fans, particularly in the south east corner, was unacceptable.
"Punches were thrown and some tried to break through the police line. We will be reviewing CCTV footage of the South-East corner and working with Manchester City to identify any individuals involved in disorder. Any supporters who saw coins being thrown and people causing trouble should get in touch."
Meanwhile, the 21-year-old City fan who stormed the pitch has had his season ticket revoked.