The Metropolitan Police has confirmed that four people have been arrested following disturbances at the Emirates Stadium on Thursday night.Arsenal's Europa League home encounter against Cologne, originally scheduled to begin at 8:05 pm BST, was delayed by an hour due to trouble outside the ground prior to kickoff.Also, Read; Arsenal in hot water with UEFAAround 20,000 supporters of the Bundesliga outfit are believed to have descended to the Emirates for the match, despite the allocation being just under 3,000 tickets. Inside the ground, images and footage appeared to show thousands of Koln fans in the home sections, with some barging through barriers as mounted police attempted to contain them.A statement from the Met Police read: "Officers responded to reports of disorder at the Emirates Stadium earlier this evening where fans gathered for the Arsenal vs FC Koln match. "A policing plan is in place for the game and additional officers were deployed."Arrests at 2141hrs = four people have been arrested on suspicion of public order offenses."Confirmation of the match delay came through at just after 7 pm.