18 sailors aboard a submarine docked in Mumbai are feared to be dead after the vessel exploded on Wednesday, in one of the most horrific accidents India has seen in years.

Some of the sailors, all of whom were Indian, were reported to be definitely deceased, Defense Minister A.K. Antony told NBC. He did not specify how many had died, nor did he release any names.

"There are some people who are trapped on board, we are in the process of trying to rescue them," P.V.S. Satish, navy spokesperson explained.

According to the Associated Press, the Russian-crafted INS Sindhurakshak, a submarine fueled by diesel gas, exploded twice, then burst into flames while berthed at the navy base in Mumbai.

The orange-red flames licked at the murky water, after the torpedo compartment in the submarine lit up and launched an enormous fireball into the sky. Sailors stationed nearby told AP they jumped back in fright-some even leapt into the ocean.

Navy chief Admiral D.K. Joshi also stated that some of the arms on the submarine also exploded during the twin blasts.

Navy officials reported that divers who had been sent to search for the sailors on board had not yet found any bodies.

"We hope for the best but we have to prepare for the worst," Joshi wryly told the press hours after the explosion.

An investigation into the cause of the explosion and whether or not the 18 sailors are alive was launched shortly after fire fighters arrived on the scene to put out the flames that surrounded the dockyard.

Some claimed that the blast was due to a glitch on the vessel, including ex-Indian navy chief Arun Prakash, who told NBC that there is always a possibility for such an accident on these kinds of heavily armed subs.

"Lots of things are in very close proximity, there is fuel, there is hydrogen, there is oxygen, there are weapons with high explosives on board," he said. "So a slightest mistake or slightest accident can trigger off a huge accident."

Other wagered that someone could have sabotaged the submarine. Prakash claimed this was "probably the last possibility."