User blog comment:Xilinoc/Ch. 580 - THE LIGHT/@comment-2211792-20140514104343

Hmmm... The girls' powers were all displayed in the blink of an eye; is it a bad sign for them? Usually, when a Sternritter's epithet is revealed, their death is near (Bazz-B is the only exception so far). Will the one who made that explosion kill them all? There wasn't anything to build them up as a considerable threat; they were just hanging out there, watching events from afar. And now that they've stepped on the battlefield, how soon are they going to be defeated?

The explosion was definitely caused by breaching the Shakonmaku, so it's either Ichigo or the Fullbringers, sent there by Kukaku's cannon.