There was an attack and then the last half of the herd showed up?

[He was making sure he understood the order of events. What he'd gotten over the walkies was that some sound had drawn the walkers back toward Alexandria and his people were making their way back but they didn't know how fast they'd make it even if they were technically ahead of the herd.]

Who attacked us? Was it them that was honking the horn?

[honking being a misnomer as whoever'd been blowing it had been holding it down like the devil himself]