I think the following two quotes make it pretty clear that it was God Himself.
I was pointed back to faithful Noah. When the rain descended and the flood came, Noah and his family had entered the ark, and God had shut them in. Noah had faithfully warned the inhabitants of the antediluvian world, while they had mocked and derided him. And as the waters descended upon the earth, and one after another was drowning, they beheld that ark, of which they had made so much sport, riding safely upon the waters, preserving the faithful Noah and His family. So I saw that the people of God, who had faithfully warned the world of His coming wrath, would be delivered. God would not suffer the wicked to destroy those who were expecting translation and who would not bow to the decree of the beast or receive his mark. I saw that if the wicked were permitted to slay the saints, Satan and all his evil host, and all who hate God, would be gratified. And oh, what a triumph it would be for his satanic majesty to have power, in the last closing struggle, over those who had so long waited to behold Him whom they loved! Those who have mocked at the idea of the saints’ going up will witness the care of God for His people and behold their glorious deliverance. { EW 284.1}
Men will be planting and building, eating and drinking, all unconscious that the final decision has been pronounced in the sanctuary above. Before the Flood, after Noah entered the ark, God shut him in and shut the ungodly out; but for seven days the people continued their pleasure-loving life and mocked the warnings of judgment. “So,” says the Saviour, “shall also the coming of the Son of man be.” Silently, unnoticed as the midnight thief, will come the hour which marks the fixing of every man’s destiny. “Watch ye therefore: … lest coming suddenly he find you sleeping.” Matthew 24:39; Mark 13:35, 36. { HF 302.4 }