Two naval personnel were killed and at least 14 injured on Monday when the Indian Navy's guided missile frigate INS Betwa slipped while undocking at the Naval Dockyard in Mumbai where it was undergoing a refit, an official spokesperson said.
While one victim was reportedly inside the indigenously-built ship as it tumbled on its side, the other was believed to be in the waters below it.
The deceased have been identified as navy personnel N.K. Rai and Ashutosh Pandey.
Another 14 personnel were rescued from the site and their condition is reported to be stable.
Taking a grim view of the incident, Navy Chief Admiral Sunil Lanba is expected to reach here for a high-level assessment of the situation.
The Indian Navy has ordered an enquiry into the disaster.
The incident occurred around 1.50 p.m. when the 126-metre-long, 3,800-tonne ship fell on its side, with the mast hitting the dockyard floor.
"There has been an incident in the Cruiser Graving Dock, Naval Dockyard Mumbai involving INS Betwa today (Monday).
"The incident occurred during undocking evolution wherein it is suspected that the dock block mechanism has failed," said an Indian Navy statement.
Navy officials said 14 personnel were rescued from the dock with minor injuries. "All personnel are stable. Diving in progress to look for two missing crew," said an official.
The extent of damage to the 3,800-tonne Brahmaputra Class frigate, commissioned into the Indian Navy in July 2004, is being assessed and technical evaluation for making the ship upright again is in process.
One of the key warships of the Western Naval Command, INS Betwa is armed with anti-ship missiles, Barak 1 surface-to-air missiles and torpedoes and has taken part in several domestic and international operations.
Incidentally, INS Betwa had a cracked sonar dome in January 2014, or the bottom of the vessel which was the subject of a probe.
This is the third major serving Indian warship involved in a major accident while docked for repairs in the past five years.
In August 2013, 18 sailors were killed when submarine INS Sindhurakshak caught fire in Mumbai harbour.
In February 2014, a major fire aboard the nuclear submarine INS Sindhuratna left two officers dead.
