hvfsl said:
Yeah, there are certainly signs it could be Islamic extremists. Since ETA generally try to do more property damage, but Islamic terrorism is all about killing as many as possible.
ETA has a dramatic figure of deaths in its CV, and you can be sure that ETA's usual purpose has nothing to do with doing as much property damage as possible. Their main purpose is to kill, and so they recognize in each one of their manifests.
It is true that ETA's actions in the past years have been aimed to kill individuals, usually polititians, policemen and militars. ETA's griever killing up to this point, though, was a bomb in a mall in Barcelona on 1987, killing 21 civilians, so this is not, at all, the first time that ETA (if they are to be credited for this masacre) aims civilians.
We cannot know the true responsible for this repulsive act, yet. There are, still, issues that make blaming ETA for it quite understandable. In the past two months, the police deactivated two bombs in a regular train, just like the ones that were bombed today, and detained the 2 ETA activists blamed for placing those bombs, and just a week ago they detained two other ETA activists carrying an insane ammount of explosives in a van towards Madrid that, if used at once, would have caused a tragedy quite bigger than today's, according to what authorities said at that time.