Well, there was the global flood that killed most life on the planet. Or was that just allegory?

How about these?

1 Samuel 15:

3 Now go and strike Amalek, and utterly destroy all that they have, and don’t spare them; but kill both man and woman, infant and nursing baby, ox and sheep, camel and donkey.’”

Hosea 13:

16 Samaria will bear her guilt, for she has rebelled against her God. They will fall by the sword. Their infants will be dashed in pieces, and their pregnant women will be ripped open.”

Numbers 31:

17 Now therefore kill every male among the little ones, and kill every woman who has known man by lying with him.

It was arguably worse for the girls:

18 But all the girls, who have not known man by lying with him, keep alive for yourselves.

And of course, 2 Kings 2:

23 He went up from there to Bethel. As he was going up by the way, some youths came out of the city and mocked him, and said to him, “Go up, you baldy! Go up, you baldy!” 24 He looked behind him and saw them, and cursed them in Yahweh’s name. Then two female bears came out of the woods and mauled forty-two of those youths.