Srimad Bhagavatam Canto 09, Chapter 08, Text 11

SB 9.8.11

sva-sariragnina tavan
 mahendra-hrta-cetasah
mahad-vyatikrama-hata
 bhasmasad abhavan ksanat
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
By the influence of Indra, the King of heaven, the sons of Sagara had lost their intelligence and disrespected a great personality. Consequently, fire emanated from their own bodies, and they were immediately burned to ashes.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
The material body is a combination of earth, water, fire, air and ether. There is already fire within the body, and our practical experience is that the heat of this fire sometimes increases and sometimes decreases. The fire within the bodies of the sons of Sagara Maharaja became so much hotter that all of them burned to ashes. The fire’s increased heat was due to their misbehavior toward a great personality. Such misbehavior is called mahad-vyatikrama. They were killed by the fire of their own bodies because of insulting a great personality.
Srimad Bhagavatam Canto 09, Chapter 08, Text 09-10
Srimad Bhagavatam Canto 09, Chapter 08, Text 12