Three naval personnel killed at dockyard

[Armand2REP]

If the second submarine was in that dry dock, it just got wet which would set back construction quite a bit.

 

[Rahul Singh]

^^The gate was under repair so precautions must on by the time of mishap. So it depends.

A Commander, Lieutenant Commander and a Master Chief were killed. Are these senior ranks or mid-level...?

First two are mid level(commissioned) and last one is senior most (non-commissioned). Wild guessing, these three persons were CO, ExO and CoB of one of unknown number teams being trained by Navy for Arihant class SSBNs.