Russia says a soldier is missing after an attack on the headquarters of its flagship Black Sea fleet in Crimea.
Video on social media shows plumes of smoke over the building in Sevastopol, after Moscow claimed it was hit by a Ukrainian missile.
The Moscow-installed governor warned residents another attack was possible and urged people to stay inside.
It comes just ten days after Ukraine launched one of its biggest attacks of the war on the same fleet.
Sirens could be heard in the city shortly after – but Governor Mikhail Razvozhayev later said the alert was over, urging people to remain cautious.
In a Telegram post, he said: “Attention everyone! Another attack is possible. Please do not go to the city centre. Do not leave buildings.”
- Latest updates: Missile hits Black Sea fleet HQ
Last week, Ukraine attacked naval targets and port infrastructure damaging a submarine and a warship. Kyiv has hinted it was behind today’s strike but not directly acknowledged responsibility.
“We told you there’d be more,” Ukraine’s air force commander Gen Mykola Oleshchuk said on Telegram, as he thanked his pilots again.
Russia’s Black Sea fleet is an important target for Kyiv – it is seen as the flagship unit of Russia’s navy and its ships have launched missiles at Ukraine causing devastating damage.
It has also been threatening to block the Black Sea shipping routes that Ukraine has been using to export grain – which is a particular sticking point for Kyiv currently.
Separately, a dispute over grain imports in Poland is increasing diplomatic tensions after Warsaw warned it would no longer supply weapons to Ukraine.