Damn, that sucks, but not nearly as much as if it was a random explosion. I believe in this scenario, astronauts would be able to do an emergency separation, getting far away from the lower stage before it was detonated. My biggest worry from this is that human flights will be delayed (justly or unjustly.)
It appears from the video that the Dragon capsule came off intact. Crewed abort probably would've been just fine, which is indeed a relief. After all, that's the point of it.
Heard something similar on the stream just a few minutes ago. Something like: we are trying to correlate the timelines of data from Falcon to the timing of the Range Safety Officer ...(turning on?)... the flight termination system.
Edit: Falcon Launch Control on "We are trying to correlate timelines and compare data with what they were able to see with down range cameras and put together what happened. We stopped receiving data at 2 min 19 sec from the vehicle. It is still not clear exactly what happened and why... At this point we don't have additional information we can provide on NASA Television until the contingency Press Conference, no earlier than 12:30? ET."
Yeah, that one is not very obvious. Think of it like a warning: "Don't quote me on this, because if you do, you might find yourself repeating incorrect information."
A literal command of "don't quote me because I'm telling you something I shouldn't" would be something like, "Off the record, this is what happened." And yeah, that would be silly to say on the internet.
I would say that the literal aspect is the same no matter how you interpret it. It's just that jacquesm guessed the wrong reason for not quoting. It's still a command.
Press conference said that range safety didn't command the FTS (flight termination system) and there is no data (yet) that FTS enabled, but that's doesn't mean the on-board FTS didn't activate itself. It certainly looked like a controlled explosion...
Hope SpaceX bounces back with another launch. They were hoping to get the landing spot on today, and then this happens. I am feeling for the guys on the floor...
Update: Looks like the explosion was triggered by Range Control in response to non nominal flight