Revelation 9:15-19

So the four angels, who had been prepared for the hour and day and month and year, were released to kill a third of mankind. Now the number of the army of the horsemen was two hundred million; I heard the number of them. And thus I saw the horses in the vision: those who sat on them had breastplates of fiery red, hyacinth blue, and sulfur yellow; and the heads of the horses were like the heads of lions; and out of their mouths came fire, smoke, and brimstone. By these three plagues a third of mankind was killed—by the fire and the smoke and the brimstone which came out of their mouths. For their power is in their mouth and in their tails; for their tails are like serpents, having heads; and with them they do harm.