God shut Noah inside the Ark after Noah and the animals entered.
Genesis 7:16 says that those entering the ark included Noah, his family, and the animals, and then states that the Lord shut Noah in. The detail appears immediately before the Flood narrative describes the rising waters.
This wording is distinct from the earlier command for Noah to make the ark’s door. Genesis 6:16 mentions a door in the side of the vessel, but Genesis 7:16 assigns the final closing action to God. The narrative therefore presents Noah as obeying the instructions while God completes the protective act.
The verse is also a useful correction to artistic or cinematic versions that may show Noah physically closing the door himself. Such adaptations can dramatize the scene differently, but the canonical Genesis wording names the Lord as the one who shuts Noah in. The passage does not identify an angel or any human helper as performing that action.