What a horrific accident. From what I’ve read, there are no casualties: let’s hope it stays that way.
Regarding catch fences: if it can be made safer then they should. But on the other hand: those cars were travelling at 200+ kph and some were standing just metres away. Those people know/knew that motorsport is dangerous, especially oval racing. So don’t get me wrong, it’s horrible that people were injured, but at some point there is a line between what can be done to make motorsport safer and the risk that drivers and spectators take.