Before the kick-off of the Catalan derby on Saturday night, a man dressed in Barcelona colours entered the Espanyol section of the RCDE Stadium and pulled out a gun on home fans.
Provoking Pericos supporters with Cules songs whilst in the away side's shirt, there was suddenly great tension after the firearm was pulled out.
However police quickly arrested the person but not before they could fire the weapon, although it is thought to have been blanks from a non-lethal firearm.
The man in question is said to have symptoms of drunkenness.