Other than the God of Light, there were several other gods who should be suspected as well. The second most suspected one was the God of Aristocracy.
The priesthood of the God of Aristocracy did not encompass the content of protecting the civilians. But their doctrine necessitated the need for "safeguarding the glory of the aristocrats," and this naturally involved the protection of civilians. A massacre was an act that would be a severe blow to the honor of the aristocrats.
If this had been arranged by the God of Aristocracy, it would be reasonable. From all the past acts of the God of Aristocracy, it was clear that they liked engaging in intrigues and conspiracies. Doing something like that was not impossible.