The coach carrying the fans was blocked by two cars before a group of masked assailants forced their way on board, wielding hammers and telescopic batons.
Around fifty attackers are believed to have been involved, leaving ten people injured, including nine Spaniards and one Polish national.
Three of the victims required hospital treatment.
Police later discovered an abandoned car containing scarves and memorabilia in the colours of Jagiellonia Białystok, along with shears reportedly used to cut through a security fence that provided access to the highway.
Witnesses said the attackers dispersed into the surrounding area before officers arrived on the scene.
The incident occurred just hours before Jagiellonia Białystok is due to face Rayo Vallecano in a UEFA Conference League fixture at 6:45 p.m. on Thursday.
Authorities have launched an investigation, but no arrests have been made so far.
Officials are appealing for anyone with information or footage of the attack to come forward as tensions rise ahead of the high-profile European match.
(mp)
Source: RMF FM/TVP Info/X/@Jagiellonia1920/@RayoVallecano