Protests after Wednesday night's Clasico between Real Madrid and Barcelona turned violent, with several arrests and reports of injuries outside the Camp Nou.
Following the goalless draw, clashes began between police and protesters outside the ground as demonstrations continued surrounding the Catalan separatist movement
Police sources told Goal that nine people have been arrested for throwing objects at law enforcement officials.
The match between the two rivals was originally set for on October 26, but the Spanish FA decided to push back kick-off by two months after fierce protests in Barcelona regarding prison sentences handed down to several key figures in the Catalan separatist movement.
The match itself was mostly uneventful on the pitch, but it did include brief delay when fans hurled yellow balls onto the pitch.
With the match stopped, players could only watch as fans unveiled choreography in favour of Catalan independence, including banners with the messages "Spain, sit and talk" and "Freedom".
The ground itself was filled with yellow and red, the colours most closely associated with the Catalan independence movement.
"There was tension in the game and I noticed when some yellow balls fell down," said Barcelona coach Ernesto Valverde after the match.
"But nothing more. We tried to give a sense of normality."
As the game neared its conclusion an announcement was made over the Camp Nou loudspeaker for fans to avoid certain exits, as fires had already been set by demonstrators outside the ground.
When the final whistle was blown, clashes between protesters and police intensified. Reports stated that masked protesters set trash bins on fire and threw rocks and glass bottles at police, who responded by firing foam bullets.
According to a report from the AFP, 21 people were injured in the clashes, including six people who needed to be taken to a medical centre for extra care.
Barcelona and Real Madrid remain deadlocked atop the La Liga standings after the match, with both sides sitting on 36 points after 17 games.
The second Clasico of the season is scheduled for March 1 and will take place at the Santiago Bernabeu in Madrid.