"A well-prepared action" – this is how SvFF's chairman Fredrik Reinfeldt commented on the scenes that took place during the Stockholm derby between Djurgården and AIK on Sunday.

Films and pictures from the incident at Tele2 Arena show how those involved threw Bengals that created a smokescreen, and then with the protection of a black curtain in the stands changed into uniform overalls.

"A change of clothes in order to escape identification," according to Fredrik Reinfeldt.

The footage shows that at least 15 people who tried to storm the pitch were wearing identical overalls.

Disposable overalls for SEK 60

In Sweden it is possible to find a retailer of these overalls. The price per garment is SEK 60 and its primary use is described as a disposable overalls that protect during the painting process. But the owner of the company says he hasn't noticed any unusual purchases lately.

Two police officers and three security guards were slightly injured in connection with the attack. The police now have several investigations regarding violent rioting, violation of the Public Order Act, violence against a public servant and blue light sabotage. The police are now reviewing video footage from the match, but the investigation is made more difficult by the fact that those involved were masked. At the moment, no one has been arrested.