Detectives said officers are working with Manchester City Football club to identify who threw a coin at Rio Ferdinand.
Charges of those arrested included a racially aggravated public order, pitch encroachment, public order, breach of a football banning order and being drunk and disorderly.
Chief Inspector Steve Howard said: "Despite fierce rivalry and high tension there was no major disorder. However, we will continue to investigate the coin throwing incident and are determined to work with the club to bring the perpetrator to justice."
More top news
The station's decision not to renew the former London mayor's contract follows his controversial comment about Hitler supported Zionism.
Sarah Seawright's police photo was shared hundreds of times by fawning social media admirers after she was arrested for careless driving.
Zoo officials said the 17-year-old gorilla was killed to save the life of the boy who had crawled past a barrier into its enclosure.