Police have been pelted with bottles and missiles after trouble broke out between football fans following a highly-charged local derby game.
Officers arrested 23 people when Port Vale entertained rivals Wolverhampton Wanderers in League One today.
Staffordshire Police said it was "confronted by a significant group of home fans" involved in "violent disorder" who had gone out of their way to target police lines.
The force is now scouring CCTV from the day's fixture, which Wolves won 3 - 1, in a bid to trace everybody who had a hand in causing trouble.
Port Vale said it would fully back any police action against any of its fans involved.