Extra police were sent to the Emirates Stadium in north London to understanding with commotion which pennyless out at the Europa League tie.
Thousands of ticketless divided fans were refused entry.
They had progressing brought executive London to a delay and police pronounced a series of flares had been liberated by the supporters.
Posts on social media sites showed vast numbers of perfume fans singing and marching around Oxford Circus.
There were also reports of fighting inside the belligerent with FC Koln fans graphic fighting with stewards forward of the Europa League tie.
A Scotland Yard orator pronounced a policing devise had been in place for the diversion and additional officers deployed.
The orator pronounced the 5 people were arrested on guess of open sequence offences.
Arsenal released a matter on their website warning travelling fans they risked being kicked out of the belligerent if they bought tickets in the sections of the Emirates indifferent for home supporters.
Despite this, perfume fans were clearly manifest in home sections all around the track forward of the rescheduled kick-off.
Speaking after the match, which Arsenal won 3-1, Arsenal manager Arsene Wenger pronounced perfume supporters had been “very clever” to enter the track undetected, with both sides likely to face UEFA charges in the coming days.
“They were very clever…I don’t know how they managed to penetrate the fans and get everywhere but they did that very well. we don’t know if they went by Arsenal membership, on the internet… they did very well.”
Cologne manager Peter Stoger refused to be questioned on the actions of the club’s supporters: “I have no criticism about the fans,” he said.
“I’m the coach, my pursuit is the team, my pursuit is football not the fans.”
A bar mouthpiece added: “We have to first surprise ourselves and in the next few days we will speak about that.”
Scotland Yard reliable there had been no reports of any “significant incidents” following the match, which eventually kicked off at 9.05pm.
The German bar are returning to European foe for the first time in a entertain of a century.