The policeman is believed to have suffered a heart attack, the Cadena Ser radio station said. According to El Mundo newspaper, he died at a hospital after he was taken there together with another injured.
Hundreds of Russian club supporters allegedly tried to cause unrest outside the San Mames stadium in Bilbao. At least three Russians were detained. Spartak Moskva faced off against Athletic Bilbao in the UEFA Europa League.
Spartak Moskva has won the match with Athletic Bilbao with the score 2:1.