And of course once the Junkie contingent hears that one of there own has ODed out, the rest go looking for his dealer, because he has the "great stuff".
The dealers have figured this out. When they package their retail product, they make a small number of "hot shots", does with much higher potency than normal (which is easy to do if fentanyl is part of the mix.) It's pretty much guaranteed to cause an OD.