Divers on Friday recovered the bodies of three of the 18 people thought to have died aboard a submarine that sank in Mumbai harbor, an Indian navy spokesman told Efe.

The operation will continue until all the bodies are found, P.V.S. Satish said.

While many of the crew managed to leap into the water, three officers and 15 sailors were trapped aboard the diesel-powered INS Sindhurakshak when it sank in the wee hours of Wednesday after a fire and several explosions.

An investigation is under way to determine the cause of the blaze.

The heat of the fire melted portions of the sub's inner hull, twisting the hatches and making it difficult for the divers to access some compartments, India's defense ministry said Thursday.

The 16-year-old Sindhurakshak, a Russian-made vessel, underwent an $80 million overhaul following a February 2010 fire that left one sailor dead and two others injured.

This week's disaster was the Indian military's deadliest accident in decades.

The sinking of the Sindhurakshak followed Monday's launch of India's first domestically built aircraft carrier, the INS Vikrant.

Only four other nations - the United States, Russia, France and Britain - have constructed aircraft carriers. EFE