"Then the 6th 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."










Revelation 9:13-14

Apparently these are demonic angels that
had been bound in the area near the Garden
of Eden. They set out to destroy 0ne-third
of mankind.