Revelation 9:16 (KJV)

Saying to the sixth angel which had the trumpet, Loose the four angels which are bound in the great river Euphrates.

And the four angels were loosed, which were prepared for an hour, and a day, and a month, and a year, for to slay the third part of men.

And the number of the army of the horsemen were two hundred thousand thousand: and I heard the number of them.

And thus I saw the horses in the vision, and them that sat on them, having breastplates of fire, and of jacinth, and brimstone: and the heads of the horses were as the heads of lions; and out of their mouths issued fire and smoke and brimstone.

By these three was the third part of men killed, by the fire, and by the smoke, and by the brimstone, which issued out of their mouths.