I wouldn't panic yet. The group of three protesters look more like performance artists to me than members of the "black block", a term used for groups of anarchists who turn violent during demonstrations. I associate these goups mainly with groups in large urban centres in Greece, Italy and Germany, btw, not in La Rioja/Spain.
According to this
informative article in Spanish, the Logrono events are something completely different, namely a "new action of the ultrarationalist collective
Homo Velamine", who have the "admitted objective of introducing a dose of additional surrealism into daily current affairs" (=actualidad, there's probably a better translation).
In one photo, the pilgrims in Logrono are mixing with the performer-protesters and look happy, so either they agree wholeheartedly or don't have a clue of what's going on as they don't understand Spanish.
What does
mochiflautas mean?