The official says the navy believes there is no way anyone could have survived the intensity of the blasts and fire Wednesday.
The official spoke on condition of anonymity because no bodies have yet been recovered.
Officials had said earlier that there had been no contact with the sailors since the explosions, which lit up the sky above the Mumbai navy base where the vessel was docked. They said navy divers had opened one of its hatches but had not yet been able to enter the submarine because it was dark and full of muddy water.
More Nation & World Headlines
NASA opens up patents to inventors, for free The kids are all right with breaking up in person New push could revive Ex-Im Bank Ben Carson leads Clinton in key states Putin spends birthday playing hockey with NHL stars Russia fires missiles as Syrian troops launch ground push Scientists win Nobel chemistry award for work on DNA repair Nuclear smugglers sought terrorist buyers
Our new comment system is not supported in IE 7. Please upgrade your browser here.