Burnley's pre-season fixture against Hanover 96 was abandoned after hooligans went on the rampage at Turf Moor on Saturday.
Trouble broke out in the section occupied by Hanover fans, with seats thrown and reports that knives were brandished at stewards trying to keep the thugs away from the Burnley supporters.
A group of Hanover hooligans continually goaded their Burnley rivals, who were housed in the same Cricket Field Stand, as police were forced to draw their truncheons on the Germans in a bid to keep the peace.
With the situation threatening to get out of hand, the match was called off at half-time on police advice.
"Today's game has been abandoned, on Police advice," a message on Burnley's official Twitter account read.
Burnley were leading 1-0 thanks to Ben Mee's goal in their final warm-up before their Premier League opener at champions Chelsea on August 12.
Clarets boss Sean Dyche said he understood why the police had decided it was too much of a risk to finish the match.
"They called us in and said, 'Look, we're going to call it for the safety of all involved, stewards, fans, police'," Dyche said.
"The police were in the referee's room, called me, went through the procedure, and obviously we fully support the police's decision.
"Hopefully nobody has got hurt. You can't really tell what's going on from how far away we are, but it didn't look ideal.
"You hope that's gone out of the game and it generally has. The police called it early. No one wanted anything other than a game of football."