Revelation 9:17-19

17This is how I saw the horses and their riders in the vision: They had breastplates that were fiery red, hyacinth blue, and sulfur yellow. The heads of the horses were like the heads of lions, and from their mouths came fire, smoke, and sulfur.

18A third of the human race was killed by these three plagues — by the fire, the smoke, and the sulfur that came from their mouths.

19For the power of the horses is in their mouths and in their tails, because their tails, which resemble snakes, have heads that inflict injury.