John Gill Commentary 1 Kings 18:38

"Then the fire of Jehovah fell, and consumed the burnt-offering, and the wood, and the stones, and the dust, and licked up the water that was in the trench." — 1 Kings 18:38 (ASV)

Then the fire of the Lord fell An extraordinary fire from God out of heaven, as the effects of it show:

and consumed the burnt sacrifice ; as it had done in former instances, (Leviticus 9:24) (Judges 6:21) (1 Chronicles 21:26) (2 Chronicles 7:1 2 Chronicles 7:3) , and besides this, which is still more extraordinary,

and the wood, and the stones, and the dust ; of the altar, thereby signifying that even such were not to be used any more:

and licked up the water that was in the trench ; around the altar, see (1 Kings 18:32) .