Revelation 9:13-18

Then the sixth angel sounded, and I heard a voice from the four horns of the golden altar which is before God, one saying to the sixth angel who had the trumpet, “Release the four angels who are bound at the great river Euphrates.” And the four angels, who had been prepared for the hour and day and month and year, were released, so that they would kill a third of mankind. The number of the armies of the horsemen was two hundred million; I heard the number of them. And this is how I saw in the vision the horses and those who sat on them: the riders had breastplates the color of fire and of hyacinth and of brimstone; and the heads of the horses are like the heads of lions; and out of their mouths proceed fire and smoke and brimstone. A third of mankind was killed by these three plagues, by the fire and the smoke and the brimstone which proceeded out of their mouths.