Both are rather unlikely; the latter is particularly unlikely, unless somebody repealed Newton's Third Law of Motion. ("For every action there is an equal and opposite reaction.")
My demented mind can see a jihadist firing this shoulder-fired hypervelocity kinetic energy round...and the recoil knocking his a$$ through several walls, leaving a Looney-Toons-ish series of jihadist-shaped holes (c8
Most like explanation: the RPG round hit exactly the right (or wrong, depending on your perspective) spot.
Poohbah, the mental image this line creates for me is too funny to put into words. BTW you owe me a keyboard.
The HV would not be fired off the shoulder...but its launch could be masked by RPG attack...just like the Kornet attack could be which I find more plausible anyway.