A few hours before the incident,
Lucifer had almost caught the tail of the angel who had been making a mess everywhere around them. The method he use was crude. After Michael and his company gone and while Satan being busy, Lucifer had used the chance to left Hell and come back to the mortal world.
It was strange where he came to the mortal land at first. The whole sky was dark like it was in Hell when he had been sure that it should still be afternoon in the mortal world. The sun was gone, must be frightening to humans, thought Lucifer.
But what caught his eyes the most was the large red moon.
While blood moon means a lot of signs to both demons and angels, there was a few that was known the most in the kingdom of Hell. That all blood moon is the end of one's happiness. While in Heaven, he heard it from Michael how the blood moon means the mourning of a loss for angel.