(CNN) At least 10 people died after two ships under the Tanzanian flag caught fire in the Kerch Strait near Crimea on Monday evening, according to Russia's state news agency TASS, citing the Russian Maritime Agency.

"Presumably, an explosion occurred (on one of the vessels). Then the fire spread to another vessel. A rescue tug is en route," said a spokesman for the Russian Maritime Agency.

A rescue operation is underway and crew members jumped into the waters to escape the flames, Russia's transport ministry told Reuters.

The ministry added that both ships had a total of 31 crew members, including Indian and Turkish citizens.

The Kerch Strait is a key waterway that holds strategic importance for both Russia and Ukraine. It is an important economic lifeline for Ukraine that allows ships leaving the port city of Mariupol to access the Black Sea.

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