Exploding Hunters?

So as i was completing a delivery, near F1, the screen started shaking. I assumed it was a gate quake, no big deal, brace and that's that. But then, seemingly out of nowhere, a HERD of what I can only assume we're hunters came at me full sprint, launched themselves at me and dealt massive damage from the resulting bursts. No tar nearby, no time fall, nothing to suggest this would happen except the quake, but I've NEVER seen something like this before. I checked corpus and nothing. Nothing I can find online either. Anyone else experience this?