After the ark had been closed, the waters of the flood came upon the earth. So sudden did the waters come, that Jesus compared the event to His second coming:
For the coming of the Son of Man will be just like the days of Noah. For as in those days before the flood they were eating and drinking, marrying and giving in marriage, until the day that Noah entered the ark, and they did not understand until the flood came and took them all away; so will the coming of the Son of Man be. (Matthew 24:37-39)Just as the Son of Man will one day suddenly return, so the flood also came suddenly upon the pre-flood world. The pre-flood world was laughing and playing, working and sweating. They were eating and drinking and giving in marriage...
And then the flood came with fury.
Water exploded out of the ground, disrupting every day life. Those who were eating must have dropped their food in alarm. Even marriage ceremonies were interrupted by heavy sheets of water toppling from the sky. Not one life was spared. Millions, and perhaps billions of un-innocent people perished. Just as many in the last days will do, perhaps some of the people of the pre-flood world cried out in terror to the mountains and the rocks, "Fall on us and hide us from the presence of Him who sits on the throne". (Revelation 6:16)
The City of Enoch, one of the most ancient cities in the world, was thrown into devastation along with every other human settlement. The entirety of the pre-flood world had followed in the footsteps of Cain. For 120 years, they had chosen the bed of demons over the joy of knowing God. Now there was no time left to choose. There was no more mercy left, but only a terrifying expectation of judgment (Hebrews 10:27).
The Destruction of The City of Enoch (Part 1) - Genesis 7:17-18
Noah's Timely Entry (Part 1) - Genesis 7:13-15
State of the World (2349 BC): The Flood (Part 1) - Genesis 7:11
120 More Years of Mercy - Genesis 6:3