what should we believe?, page-29

Cmte, The Scripture reference to 'fallen angels' and 'hybrids' took place prior to the flood of Noah's day. Genesis 6:1-4. The same event is spoken of at Jude 6.
Angelic sons of God had relations with women, and the women bore children who grew to possess extraordinary strength. They came to be known by the Hebrew term “Nephilim.” We are told: “The Nephilim proved to be in the earth in those days, and also after that, when the sons of the true God continued to have relations with the daughters of men and they bore sons to them, they were the mighty ones who were of old, the men of fame.” (Genesis 6:4) The Nephilim were much to be feared. The word “Nephilim” means “Fellers,” those who cause others to fall down. They were killers whose violent exploits are likely echoed in ancient myths and legends.
The Flood forced the angels back into the spirit realm. Jehovah, however, prevented them from resuming “their original position.” (Jude 6) The Bible states: “God did not hold back from punishing the angels that sinned, but, by throwing them into Tartarus, delivered them to pits of dense darkness to be reserved for judgment.”—2 Peter 2:4.
Tartarus is not a particular location; it is a prisonlike, abased condition that limits the activity of these outcasts. The demons can no longer materialize, but they still have great power and influence over minds and lives. They can possess humans and animals. (Matthew 12:43-45; Luke 8:27-33)