Russia's submersible / Photo from Oruzhiye RF

Russia's Defense Ministry says a fire on one of its deep-sea research submersibles has killed 14 crew members.

The ministry said on July 2 that the tragedy took place the previous day as the vessel was carrying out a survey in Russian territorial waters, Radio Free Europe / Radio Liberty (RFE/RL) said.

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A Defense Ministry statement said that the sailors died as a result of inhaling combustible fumes aboard the research vessel, which was conducting biometric measurements on the floor of the ocean.

The submersible is now at a navy base in the northwestern city of Severomorsk near Murmansk on the Barents Sea, officials said.

An investigation has been launched.