Revelation 9:13-18

Then the sixth angel sounded [his trumpet], and I heard a solitary voice from the four horns of the golden altar which stands before God, saying to the sixth angel who had the trumpet, “Release the four angels who are bound at the great river Euphrates.” So the four angels, who had been prepared for the [appointed] hour and day and month and year, were released to kill a third of mankind. The number of the troops of cavalry was twice ten thousand times ten thousand (two hundred million); I heard the number of them. And this is how I saw the horses and their riders in my vision: the riders had breastplates [the color] of fire and of hyacinth (sapphire blue) and of brimstone (yellow); and the heads of the horses looked like the heads of lions; and from out of their mouths came fire and smoke and brimstone (burning sulfur). A third of mankind was killed by these three plagues—by the fire and the smoke and the brimstone that came from the mouths of the horses.