The accident took place in the early hours of Wednesday. The injured sailors, who fell unconscious from suffocation, were airlifted to a Navy hospital in Mumbai. Reports suggest that a fire may have broken out on the vessel.
The INS Sindhuratna was being sea tested after a refit, about 40 to 50 km off the Mumbai coast when the smoke was detected. The senior-most submarine officer of the Western Naval Command was on board.
The Russian-origin Kilo Class submarine was carrying no weapons or ammunition. Since it was still in testing mode, it had not been placed under operational command yet.
While the Indian Navy is yet to release an official statement on the mishap, sources in the Navy have reportedly told news agency PTI that a leakage in the battery compartment of the submarine could have caused the smoke.
This is the 10th mishap involving an Indian Navy warship and the third submarine accident in the last seven months.
In August last year, Navy submarine INS Sindhurakshak sank in the Mumbai harbour after an explosion on board, killing 18 sailors. (Salvage contract of INS Sindhurakshak to be finalised soon: Navy chief)
Earlier this month, an amphibious warfare vessel INS Airavat ran aground after which its commanding officer was stripped of his command duties.