MOSCOW (AP) — The Russian military says that a fire on one of its deep-sea submersibles has killed 14 sailors.

The Defense Ministry says that the blaze erupted Monday while the vessel was performing tests in Russia's territorial waters.

The ministry said in a statement Tuesday that the fire was extinguished thanks to the crew's self-sacrifice.

It added that the submersible is now at the Arctic port of Severomorsk, the main base of Russia's Northern Fleet. An official investigation has started.