Police is being investigated to see if what they did was correct or not.
What I fail to understand is why did they need to cause a scene at an airport, blocking the arrival gate and triggering the police charge.
I mean, mate, airports are known to be a place where police don't fuck around because they are on "max alert" mode; even more if we talk about a region that, not so long ago, was terrorized by ETA. Now we can argue if what the police did was right or wrong and, seeing these images, I'd say it's fair to open an investigation to know it and punish them if they acted wrongly. But seriously, on an airport, in the Basque Country? Do you have a death wish?