This was the Ertzaintza (Basque regional police). They were created during the harshest days of ETA, so many of them have a long history of not being exactly gentle with far leftist groups. And justice has not been exactly harsh with their abuses of authority, because they were battling terrorists, and judges were ETA targets too. You know the drill.
I suspect someone got too far and too public this time. All of the main Basque parties are pro-Palestinian, so it is a serious blunder politically speaking.
@jgg @peter That is true. The major left-wing party in the Basque Country also ocassionally attack Ertzaintza trying to remove some power from it. For example this proposal of taking the guns from the officers. https://www.deia.eus/actualidad/politica/elecciones-euskadi/2024/04/04/eh-bildu-plantea-desmilitarizar-ertzaintza-8076141.html