LazyGun, this wasn't a practical joke; practical jokes are aimed at someone and with a desired outcome in mind.
This was a prank call, and the point with such calls is that the outcome is *never* precisely foreseeable. You just d it to see what will happen. So it's always open to perpetrators to claim they didn't know what was going to happen. Of course they didn't - but they went ahead with it anyway.
But actions do have consequences and it's not at all unfair to require people to take responsibility for them. On the contrary, it's one of the foundations of the way our society works.
The DJs agree with me on this, of course. Only yesterday they were boasting of their succeess. "A career highpoint", one of them called it. The station was still advertising it hours after the nurses's death was reported.
Well, if they're so happy to claim the credit when things go right, there's nothing wrong in saying they should take the blame when things go wrong. And the social media furore now is in porportion to the adulation they were getting yesterday - another consequence of their actions which they must face.
The station's claim that "it wasn't foreseeable" is self-serving, and a shameful attempt to blame the victim. So it's unforeseeable that if you humiliate someone in front of the whole world, they will feel sucidal? Well, if they couldn't foresee that they shouldn't have made the call.