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 (on Saturday) has no place in football, and certainly not in Lancashire."Children and families were in attendance at what was a pre-season friendly match, which should have passed peacefully and without incident - but which ended up being abandoned due to the behaviour of some of the travelling Hannover fans."Overnight we have collated and trawled through footage of the disorder, but we believe there will be more people who have videos on their phones which could help with our ongoing investigation."Anybody who has such footage is asked to send it to us as soon as possible."Bithell had revealed on Saturday that a "robust policing operation" was in place based on "pre-game intelligence" and that additional resources from across the county had been brought in.As a result of the violence, a police officer suffered a head injury and was treated at Burnley General Hospital. He has since been discharged.Two stewards who suffered minor injuries were treated at the scene, and one, who suffered a dislocated shoulder, is currently undergoing treatment in hospital.Burnley boss Sean Dyche backed the decision of the police to bring a premature end to the friendly.He told the local press: "They called us in and said 'look, we're going to call it for the safety of all involved, stewards, fans, police etc'."That was pretty early. The police were in the referee's room, called me, went through the procedure, and obviously we fully support the police's decision."Hannover released a statement on their website on Saturday night condemning the scenes.It read: "Our attitude is clear: Hannover 96 condemns the incidents in the stadium and dissociates itself vehemently from any kind of violence."The club does not yet have any clear insights into the progress of the events. This information will be gathered in consultation with the police, the hosts from Burnley and fan representatives."