A police officer and two stewards were injured during crowd trouble which forced the abandonment of Burnley's friendly against Hannover on Saturday.
Lancashire Police have opened an investigation following the disorder, which occurred after fans of the Bundesliga side charged towards home supporters during the first half at Turf Moor.
The Clarets were leading 1-0 at half time thanks to a goal from Ben Mee when the announcement of the abandonment came.
Lancashire Police chief superintendent Chris Bithell said: 'The disorder we saw has no place in football, and certainly not in Lancashire.