The Indian Navy suffered a huge blow Wednesday when a frontline submarine exploded and sank here at dawn with 18 sailors after two explosions turned it into a deadly ball of fire.
The deep sea attack vessel INS Sindhurakshak, recently refurbished in Russia, suffered an unexplained explosion just after Tuesday midnight and an immediate deafening blast heard almost in the whole of south Mumbai.
Naval officials said the rapid spread of the blaze and the intensity of the explosions left the trapped 18 sailors, including three officers, with apparently no chance of escaping.
"We cannot rule out sabotage," navy chief Admiral D.K. Joshi told the media after Defence Minister A.K. Antony visited the disaster site at the Mumbai naval dock.
"But indications at this point do not support the (sabotage) theory," he said. "At this point of time we are unable to put a finger on what exactly could have gone wrong."
An inquiry set up to probe the disaster will submit its report within four weeks.
It was the worst disaster to hit the Indian Navy, which has increasingly sought to dominate the expansive Indian Ocean region with blue water operational capability.
The incident came two days after India acquired its first indigenous aircraft carrier, INS Vikrant. The past week also saw the nuclear reactor that propels Arihant, the country's first ballistic missile submarine, going critical.
TV grabs of the incident and amateur video shots showed a huge ball of flame erupting on the horizon of the Mumbai harbour and lasting for nearly three hours before it was brought under control around 3 a.m.
The vessel eventually sank around dawn with the 18 officers and sailors.
Admiral Joshi appeared to indicate that all of them may have perished when he said: "We hope for the best and prepare for the worst."
By afternoon, navy divers had entered the sunk vessel after forcing open the jammed hatch.
Joshi ruled out any link between Wednesday's incident and a 2010 accident INS Sindhurakshak had suffered.
The Mumbai Fire Brigade managed to avert a greater tragedy by saving a second submarine at the dock.
Deputy Chief Fire Officer P.S. Rahandale told IANS that he saw another submarine berthed five-six metres away from the burning INS Sindhurakshak.
"We built a wall of water-jets between Sindhurakshak and the other vessel, thereby giving it a safe window to sail to safety," he said.
Admiral Joshi said any number of factors could have led to the "major catastrophe"
He said the submarine had a large stock of ammunition, fuel and oxygen water. "Any combination of any of these malfunctioning could have resulted (in the explosion)."
He said the submarine had inbuilt safety measures but "obviously they have not functioned".
In losing INS Sindhurakshak, the navy may have lost certain key maritime capabilities but "nothing is insurmountable", former naval chief Admiral Arun Prakash, who retired in 2006, told IANS in Goa.
INS Sindhurakshak was a diesel-electric submarine that returned home last year after a major refit at Russia's Zvezdochka shipyard.
It displaces 2,300 tonnes, carries 52 crew members, has a top speed of 19 knots (35 km per hour) and diving depth of 300 metres.
With over 58,000 personnel, the Indian Navy boasts of a large operational fleet that includes an aircraft carrier, an amphibious transport vessel, eight guided missile destroyers, 15 frigates, a nuclear powered submarine, 14 conventional submarines, 24 corvettes, 30 patrol vessels, seven mine counter measure vessels and auxiliary ships.
