MOSCOW (AP) — One of the protesters who barged onto the field last year to disrupt the World Cup final in Russia was briefly detained Tuesday by police in Moscow, activists said.

Veronika Nikulshina of the Pussy Riot protest group was reportedly detained along with two others as they were heading to attend a theater awards ceremony at the Bolshoi Theater. Fellow Pussy Riot member Verzilov tweeted that Nikulshina and her companions were nominated for the Golden Mask award.

Verzilov said police didn’t explain the reason for the detention and freed the trio a few hours later.

Verzilov, Nikulshina and two other activists served 15-day jail sentences last year after they disrupted July’s World Cup final, running onto the field wearing police uniforms.

In September, Verzilov was treated at a Berlin hospital for a suspected poisoning. Doctors were unable to determine the cause, but fellow activists suspected foul play.