Rev 8 tells us about the seven angels and their trumpets. After the seventh seal was opened, there was a period of silence and then the four of the seven angels each sounded their trumpets, which caused destruction of 1/3 of the earth, 1/3 of the sea, 1/3 of the fresh water supply, and the sun, moon, and stars. As if this wasn't enough, John hears from "midair call out in a loud voice: Woe! Woe! Woe to the inhabitants of the earth, because of the trumpet blasts about to be sounded by the other three angels!".