The story of Bhaumāsura—how he kidnapped and made captive sixteen thousand princesses by collecting them from the palaces of various kings and how he was killed by Kṛṣṇa, the Supreme Lord of wonderful character—is all described by Śukadeva Gosvāmī to King Parīkṣit in Śrīmad-Bhāgavatam. Generally, the demons are always against the demigods. This demon, Bhaumāsura, having become very powerful, took by force the umbrella from the throne of the demigod Varuṇa. He also took the earrings of Aditi, the mother of the demigods. He conquered the portion of heavenly Mount Meru known as Maṇi-parvata and occupied it. The King of the heavenly planets, Indra, therefore came to Dvārakā to complain about Bhaumāsura before Lord Kṛṣṇa.
Hearing this complaint by Indra, the King of heaven, Lord Kṛṣṇa, accompanied by His wife Satyabhāmā, immediately started for the abode of Bhaumāsura. The two of them rode on the back of Garuḍa, who flew them to Prāgjyotiṣa-pura, Bhaumāsura's capital city. To enter the city of Prāgjyotiṣa-pura was not a very easy task, because it was very well fortified. First of all, there were four strongholds guarding the four directions of the city, which 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 by electric wires. The next fortification was of anila, a gaseous substance. After this, there was a network of barbed wire constructed by a demon of the name Mura. The city appeared well protected even in terms of today's scientific advancements.
When Kṛṣṇa arrived, He broke all the strongholds to pieces by the strokes of His club and scattered the military strength here and there by the constant onslaught of His arrows. With His celebrated Sudarśana cakra He counteracted the electrified boundary, annihilated the canals of water and the gaseous boundary, and cut to pieces the electrified network fabricated by the demon Mura. By the vibration of His conchshell, He broke the hearts of the great fighters and also broke the fighting machines that were there. Similarly, He broke the walls around the city with His invincible club.
The vibration of Lord Kṛṣṇa's conchshell sounded like a thunderbolt at the time of the dissolution of the whole cosmic manifestation. The demon Mura heard the vibration of the conchshell, awakened from his sleep and 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 cosmos, and his temper was like blazing fire. The effulgence of his body was so dazzling that he was difficult to see with open eyes. When he came out, he first took out his trident and rushed the Supreme Personality of Godhead. The demon Mura in his onslaught was like a big snake attacking Garuḍa. His angry mood was very severe, and he appeared ready to devour the three worlds. First of all he attacked the carrier of Kṛṣṇa, Garuḍa, by whirling and then throwing his trident, and through his five mouths he vibrated sounds like the roaring of a lion. These roaring vibrations spread all over the atmosphere until they extended all over the world and into outer space, up and down and out to the ten directions, rumbling throughout the entire universe.