At least 101 people are unaccounted for after an Iranian naval ship was struck and sunk in a suspected submarine attack off Sri Lanka’s southern coast, according to sources in the country’s navy and defence ministry. They say one person has died and around 78 are being treated for injuries after a frantic overnight rescue operation.

The vessel — identified by regional media as the Iranian frigate IRIS Dena, recently in India for naval exercises — sent a distress call early Wednesday local time before disappearing beneath rough seas off Galle. Sri Lanka’s navy says dozens of survivors were pulled from the water and rushed to the National Hospital in Galle.

In a confusing information battle, an official navy spokesman publicly rejected reports that 101 people were missing, insisting only 32 injured had been brought ashore, even as anonymous military sources repeated the far higher figure and confirmed the ship had sunk.

What exactly hit the vessel remains the most explosive question. Sri Lankan and Iranian officials have not named a culprit, but US officials speaking privately to reporters say an American submarine carried out the strike — a claim Washington has not formally detailed and Colombo has not endorsed.

For families in Iran and Sri Lanka glued to live coverage, the horror is growing by the hour: grainy footage of a listing warship, packed hospital corridors in Galle, and a mounting list of missing sailors. Strategists warn this is now a turning point in the widening Iran conflict — the first sinking of a warship by submarine torpedo in decades, and a shock that could redraw the rules of naval warfare in the Indian Ocean.