Indian navy divers have found the bodies of four of 18 sailors who were inside a submarine when some of its weapons detonated, setting off a fire.
There has been no sign of life from the INS Sindhurakshak since it sank on Tuesday night following two big explosions in what was the biggest loss for the navy in four decades.
The Defence Ministry said a large amount of seawater had entered the diesel-powered submarine, hampering visibility, while the damage caused by the explosion was blocking access to some areas.
The 16-year-old submarine, which had suffered an accident in 2010, had recently returned from Russia after a two-and-a-half year upgrade of its electronic warfare and integrated weapons control systems.
The explosions took place in the vessel's forward section, where its torpedoes and missiles are stored.
INS Sindhurakshak is a Kilo class vessel which were built in Soviet and later Russian shipyards for the Indian navy from 1985 to 2000.
The navy has ten of the submarines and four German HDW boats.