"The story of Bhaumasura--how he kidnapped and made captive sixteen thousand princesses by collecting them from the palaces of various kings and how he was killed by Krsna, the Supreme Lord of wonderful character--is all described by Sukadeva Gosvami to King Pariksit in the Srimad-Bhagavatam. Generally, the demons are always against the demigods. The demon, Bhaumasura, having become very powerful, took by force the umbrella from the throne of the demigod Varuna. He also took the earrings of Aditi, the mother of the demigods. He conquered a portion of heavenly Mount Meru and occupied the portion which was known as Mani-parvata. The king of the heavenly planets, Indra, therefore came to Dvaraka to complain about Bhaumasura before Lord Krsna.
Hearing this complaint by Indra, the King of heaven, Lord Krsna, accompanied by His wife Satyabhama, immediately started for the abode of Bhaumasura. Both of them rode on the back of Garuda, who flew them to Pragjyotisa-pura, the capital city of Bhaumasura. It was not a very easy task to enter the city of Pragjyotisa-pura, because it was very well fortified. First of all, there were four formidable forts guarding the four directions of the city, and it was well-protected on all sides by formidable military strength. The next boundary was a water canal all around the city, and in addition the whole city was surrounded with electric wires. The next fortification was of anila, a gaseous substance. After this, there was a network of barbed wiring constructed by a demon of the name Mura. It appeared that the city was well-protected even in terms of today's scientific advancements.
When Krsna arrived, He broke all the forts to pieces by the strokes of His club, and the military strength scattered here and there by the constant onslaught of the arrows of Krsna. With His celebrated Sudarsana cakra He counteracted the electrified boundary; the channels of water and the gaseous boundary were made null and void, and He cut to pieces the electrified network fabricated by the demon Mura. By the vibration of His conchshell, He not only broke the hearts of the great fighters, but also the fighting machines which were there. Similarly, the walls around the city were broken with His invincible club.
The vibration of His conchshell sounded like the thunderbolt at the time of the dissolution of the whole cosmic situation. The demon Mura heard the vibration of the conchshell, awakened from his sleep, and personally came out to see what had happened. He had five heads and had long been living within the water. The Mura demon was as brilliant as the sun at the time of the dissolution of the cosmic manifestation, and his temper was like blazing fire. The effulgence of his body was so dazzling that it was difficult to see him with open eyes. When he came out, he first took out his trident and began to rush the Supreme Personality of Godhead. The onslaught of the demon Mura was like a big snake attacking Garuda. His angry mood was very severe, and he appeared ready to devour the three worlds. First of all he attacked the carrier of Krsna, Garuda, by whirling his trident and he began to vibrate sounds through his five faces like the roaring of a lion. The roaring produced by the vibration of his mouths spread all over the atmosphere until it extended not only all over the world, but also into outer space, up and down and in and out to the ten directions. In this way, the sound was rumbling throughout the whole universe.
Lord Krsna saw that the trident of the Mura demon was gradually rushing toward His carrier, Garuda. Immediately, by a trick of His hand, He took two arrows and threw them toward the trident, cutting it to pieces. Simultaneously, using many arrows, He pierced the mouths of the demon Mura. When he saw himself outmaneuvered by the Supreme Personality of Godhead, the Mura demon immediately began to strike Him in great anger with his club. But Lord Krsna, with His own club, broke the club of Mura to pieces before it could reach Him. The demon, bereft of his weapon, decided to attack Krsna with his strong arms, but by the aid of His Sudarsana cakra, Krsna immediately separated the demon's five heads from his body. The demon then fell into the water, just as the peak of a mountain falls into the ocean after being struck by the thunderbolt of Indra."
Krsna Book, Chapter 59
Bhaktivedanta Book Trust. Excerpted from text and purport of HDG A.C. Bhaktivedanta Swami Srila Prabhupada.