14 Russian navy sailors were killed in a submersible vessel fire

Russian President Vladimir Putin pulled out of a planned event centered on tourism on Tuesday after receiving word that 14 Russian sailors were killed when a fire broke out on Monday in a submersible research vessel. It was the worst naval incident in Russia in a decade.

The Russian Defense Ministry said the sailors died from smoke inhalation. It is unclear exactly when on Monday the fire broke out and when the deaths were first reported to Russian officials like Putin.

The vessel, designed for deep-sea exploration to study the ocean floor, is reportedly linked to a secret nuclear submarine project, and crew members were reportedly performing biometric measurements in Russian territorial waters.

The Defense Ministry did not give any details about the cause of the incident, though the vessel is reportedly now at the Russian Northern Fleet's Severomorsk base in the Murmansk region on the Barents Sea coast in the northernmost reaches of the country, above the Arctic Circle. An investigation into the cause of the fire is reportedly underway, though a military expert who spoke anonymously with Agence France-Presse said that it's unlikely the fire happened during scientific research. "Usually it's a cover for different type of work conducted on the seabed," like laying cables, the expert said.

The incident is the latest in a string of disasters experienced by Russia's navy, Agence France-Presse reports. AFP adds that Monday's incident is particularly reminiscent of the sinking of the Kursk submarine in 2000 that caused 118 deaths.