What happened after the flare was seen in the evening sky?
The soldiers under the human general had those captured beastmen gathered and massacred by his soldiers. After they were dead, they were killed to be burnt to a small hill of ashes then left there to be blown away by the wind. Moreover, the soldiers intentionally left this pile of ashes at the forest between the city and the borders. Unless one intentionally entered the forest no one would see it at all.
