Mourners gathered to lay flowers and light candles to honor 14 sailors who died when a fire broke out in a Russian submarine.
Now it's been revealed that the top-secret military vessel was nuclear-powered.
President Vladimir Putin disclosed the information in a Kremlin meeting on Thursday (July 4).
Prompting the country's defence minister to assure him that the submarine's nuclear reactor had been contained.
Russian officials have faced accusations of trying to cover up the full details of the accident.
The men were killed carrying out what the defence ministry called a survey of the sea floor near the Arctic.
Putin said seven held the rank of captain, first class, and two were holders of the Hero of Russia - the highest military award issued in the post-World War Two period.
The Ministry of Defence said the incident took place on Monday (July 1).
But it was not officially disclosed until late on Tuesday (July 2).
And there was no indication until Thursday whether the vessel had a nuclear reactor on board - Despite intense interest in that question from neighbouring Norway.
Some Russian media criticized what they said was a lack of transparency.
And drew parallels with the dearth of official information during the meltdown of a Soviet nuclear reactor in Chernobyl in 1986.