Real Madrid's 5-1 Champions League win at home to Legia Warsaw on Tuesday night was marred by violence outside the stadium involving Polish ultras and Spanish police.
The Group F fixture had been deemed "high risk" by the authorities in the Spanish capital concerned about the visit of Legia's more radical supporters, and although the security presence was strengthened considerably the evening saw a number of serious incidents around the Bernabeu.
An organised group of fans advanced together to the stadium and threw bottles at police who were waiting to try and control the situation.
Police responded with a baton charge and by firing rubber bullets into the group. Some ultras aimed kicks and punches at individual riot police, and one fan among the 4,000 official allocation told police to back off using a megaphone. Five Polish fans and two police were treated for injuries by ambulance staff at the ground.
Scarves and food were also stolen from stalls close to the stadium, while journalists attempting to film the incidents were threatened. Local fans attending the game did not get involved, although there was disruption at entrances to the Bernabeu close to where the violence was taking place.
Spain's national police tweeted later on Wednesday night that the "#RealMadridLegia operation had ended with 12 arrests. Remember, on and off the pitch, ALWAYS: #respect and #sportsmanship."
- Policía Nacional (@policia) October 18, 2016
Asked about the incidents at the post-game news conference, Legia coach Jacek Magiera suggested that the actions of a few individuals should not take away from what he said was the "extraordinary" support his team received.
"Our fans create an extraordinary atmosphere, their travelling support is the strongest in Europe in terms of numbers," the former Legia midfielder said. "There are of course some individuals who damage the club's image. We must make sure this does not happen again in future."
Following racist behaviour and crowd disturbances including stewards being pepper-sprayed during Legia's 6-0 home defeat to Borussia Dortmund in September, UEFA ordered a full stadium closure for their next home game -- against Madrid in Warsaw on Nov. 2.
Legia were ordered to play two European home matches behind closed doors for racism by their fans following an away match at Belgian club Lokeren in November 2014, while fans displayed a "Jihad Legia" banner before a Europa League game at Hapoel Tel Aviv in 2011. UEFA also sanctioned fans' racist behaviour by closing a section of Legia's stadium at a Champions League playoff in the 2013-14 season.