Two personnel were killed on Monday and 15 others injured when INS Betwa, a guided missile frigate, tipped over during undocking at Naval Dockyard in Mumbai.

"There has been an incident in the cruiser grounding dock at Naval Dockyard in Mumbai involving INS Betwa. The incident occurred during undocking evolution wherein it is suspected that dock blocks mechanism failed," navy spokesperson Capt D K Sharma said.

Explaining the situation, he said the 3,850-tonne ship, having a length of 126 metres, tipped over while it was being undocked. The mast of the ship hit the dockyard ground, he said. It was docked for repairs and while being returned to the water -- a process that involves tipping the ship -- the system tripped and the entire ship fell sideways. The main mast of the frigate broke.

#UPDATE INS Betwa incident at Mumbai dockyard: Two dead, others being treated for minor injuries — ANI (@ANI_news) December 5, 2016

The incident occurred at about 1.50 pm. This Brahmaputra class ship, a guide missile frigate, was commissioned into the Indian Navy in 2004 and has participated in several exercises.

In January 2014, the same ship had run aground and collided with an unidentified object while approaching the Mumbai naval base. The sonar system of the frigate was cracked, leading to faulty readings and an ingress of saltwater into sensitive equipment.

Monday's incident is yet another mishap of the India Navy. The earlier being INS Sindhurakshak, among others.

With agency inputs