Indian divers searched around the clock for 18 sailors feared dead after explosions partially sunk an Indian Navy submarine in Mumbai.
Several sailors managed to jump for freedom after two blasts shot fire into the sky on Wednesday.
The blast was believed to have been from an ordinance onboard that exploded while the submarine was docked.
The navy watchmen manning the vessel have not responded to divers and there are no sounds coming from the submarine.
Heavy pumps are being used to take out water from the vessel which is said to be inundated.
"There would have been signs of life through tapping of the hull by the sailors, which is a known procedure for the rescue of sunken submarines," said S.C.S. Bangara, a retired navy vice admiral, according to the Associated Press.
"The trapped personnel have not been sighted nor recovered," the navy said in a statement.
"The heat of the explosion has melted parts of the internal hull, deforming the submarine hatches and preventing access to compartments," the navy said, according to the AP.
An eyewitness video showed the explosion light up the night sky.
The Indian navy says it is still investigating the cause of the incident which is believed to have possibly originated from torpedoes or cruise missiles.
The 16-year-old submarine had just returned from a refitting and refurbishment in Russia in April and had been approved for use by the Indian Navy.