Acting Superintendent Vernon Francis has revealed that he was "quite surprised" by the level of crowd trouble before, during and after Leeds United's Carling Cup tie with Manchester United last night.
Twenty-one arrests were made and two police officers were injured during clashes outside of Elland Road and Supt Francis has confirmed that an investigation to identify further offenders is ongoing.
"I was quite surprised at how ferocious it was last night," Supt Francis told Sky Sports News. "It was very violent and we condemn that violence.
"There were clearly people who turned up intent on causing violence and nothing else last night.
"There is a full post-match investigation under way."