Friday 15 September 2017 07:20, UK
Arsenal's Europa League clash with Cologne at the Emirates was delayed by an hour over a "crowd safety issue".
Thousands of Cologne fans gathered outside the stadium without tickets for the match, with home supporters unable to gain entrance to turnstiles because of the large number of fans on the concourse.
The Metropolitan Police deployed additional officers to the Emirates and said it was "dealing with disorder at the Emirates Stadium", before later confirming four people had been arrested on suspicion of public order offences.
Gates did open for the sold-out match shortly before 8pm, five minutes before the original 8:05pm scheduled kick-off time, but scuffles broke out inside the ground as supporters inside the home end could be seen jumping into the away end.
As Cologne fans began to sing, large groups of fans either side of the away end began to clap and bounce in unison.
Officially there was space for 3,000 away fans, but it is understood up to 20,000 Cologne supporters have made the trip to London.
The match did kick off at the revised time of 9:05pm.
Fans took to the streets in their numbers earlier in the day, with social media posts showing hordes of supporters singing and marching around Oxford Circus hours before the scheduled kick off.
Ahead of the delay, Arsenal's official website warned Cologne fans they faced being asked to leave the stadium if they purchased tickets in the home sections of the ground.
"Please note visiting supporters that purchase a ticket in the home end for this fixture are likely to be ejected from the stadium," a statement on their website read.
Cologne currently sit bottom of the Bundesliga having lost all three of their league games so far - but they reached the Europa League having finished fifth last season.
Head coach Peter Stoger was asked on the eve of the game if he had a message for the thousands of fans making the trip, to which the Austrian replied: "Enjoy the pubs!"
