Answer
If a marine casualty occurs on or near the Indian coast, the practical first-reporting point is the DG Shipping Communication Centre (DGCOMM Centre). DG Shipping describes DGCOMM as the 24×7 first point of contact for casualties involving an Indian vessel, any vessel in Indian waters, or an Indian national.
DG Shipping's casualty procedure says casualty information from the ship, owner/manager, port, local MMD or other source is relayed to DGCOMM Centre, which then coordinates with the DG Shipping casualty branch, the nearest MRCC/Indian Coast Guard and the relevant MMD.