Literary note: this is the beginning of the third stanza, and the focus returns to the people.
Scriptural analysis: The image of burning is both literal and symbolic. Burning usually accompanied ancient warfare as a tactic of destruction of sustenance and pride of place. There were many more flammable buildings in the ancient world than inflammable ones, and fires could run rampant through cities.
The specific image noted here is of the land, however, for it too will be devastated, a theme of earlier Isaianic prophecy. One should remember, however, that burning is a purification process, and while it brings great destruction, can also be an instrument of renewal. On relation to the land, burning has even been used as a mode of replenishing the soil. Therefore, while the image is one of destruction, there is yet place in the vision for the eventual redemption.