At that time the Danava king Bali was celebrating a HorseSacrifice in the nether regions. Those great Asuras who were with himn in those regions or who were living in the bowels of the Earth, were not burnt.
बलिस्तु यजते यज्ञमश्वमेधं महीं गतः। येऽन्येऽधस्था महीस्थाश्च ते न दग्धा महासुराः॥