A step behind Harry, Sirius froze. There was mud -- clods of it, falling -- but that wasn't the problem. Flesh fell as well. The people were not merely injured, but long dead.
Leaping to his godson's side, he called back to the others. "Inferi! Wands out!"
Damn it! Gaius was never in any of the fights with Inferi. He might not know what to do!