Two injured as clashes follow West Midlands derby game
Two people were taken to hospital with head injuries as clashes followed Saturday's derby match between Birmingham City and Wolves.
Police said there were "a few pockets of disorder" and that CCTV around Birmingham's St Andrew's ground and the city centre would be reviewed.
Four people were arrested for disorder-related offences.
Birmingham City won 2-1 to dent Wolves' hopes of promotion from the Championship.
The match was "comprehensively risk-assessed over many weeks" and there was "a strong police presence in and around" St Andrew's, the West Midlands force said.
Match commander Ch Supt James Andronov said: "Some people have questioned the decision to allow both sets of fans to leave the ground at the same time.
"It is rare these days to hold back supporters - it's not been done at this fixture for several years - as evidence suggests to do so often increases tension and the prospect of trouble."
He said, as with all large operations, the force would review the policing of the match.