The headquarters of Russia’s Black Sea fleet caught fire after being hit by a Ukrainian missile strike, according to Moscow and its allies.
One serviceman was missing following the attack, said the Russian defence ministry which earlier stated he had been killed.
Ukraine‘s military said its forces had “successfully” struck the navy HQ in the Crimean port of Sevastopol but gave no more details.
The city’s Russian-installed governor, Mikhail Razvozhayev, said the strike caused a fire and no one was injured outside the building but he did not talk about any other casualties.
Firefighters battled the blaze and more emergency forces were being brought in – a sign of the large scale of the fire.
A stream of ambulances arrived at the building and shrapnel was scattered around an area of hundreds of metres, the Tass news agency reported, adding police asked residents to leave the city centre, where the naval HQ is located.
Mr Razvozhayev initially told Sevastopol residents that another attack was possible and urged them not to leave buildings or go into the centre.
He later said there was no longer any threat of an airstrike but reiterated that people should not go to the central part of the city.
The defence ministry said five missiles were shot down by its air defence systems responding to the Sevastopol attack.
It was not immediately clear if the HQ was hit in a direct strike or by debris from an intercepted missile.
Navy HQ attack part of well co-ordinated plan by Ukraine
Sky’s defence analyst Sean Bell said: “One of the things that that we’ve been looking at closely over the last few weeks is that the Ukrainians have been mounting a pretty intensive counter-attack, but there have also been drone attacks and missile attacks all over the place.
This is actually part of a well co-ordinated plan by Ukraine.
So one of the reasons they’re attacking the Black Sea fleet is they’re trying to push the fleet further east.
Why is that? It is because the Black Sea fleet has been providing a lot of logistic support for the Russian forces in Ukraine and therefore it’s making life more difficult for them.
Likewise on the Dnipro River, the Kakhovka Dam was blown by the Russians in June because that protected their flank. All that water has subsided now and the Ukrainians keep mounting attacks across Dnipro.
Why is that significant? Because it’s fixing Russian forces across that side of the country. In Bakhmut, which is tactically an insignificant city, the Russians have put 70,000 to 80,000 forces there because it’s so symbolic, and therefore by attacking that, Ukrainians are fixing Russian forces up there as well.
And by continuing attacks on Crimea, again, the Russian forces that would otherwise be used to bolster the frontline have had to be kept there.
Finally up in Moscow, by doing drone attacks there, Vladimir Putin will be worried about his own defences as well.
So all of this is about forcing Russia to make priorities about where it positions its military forces.
Meanwhile, Crimea has been struck by an “unprecedented” cyberattack in the wake of the missile strike, according to an official.
“An unprecedented cyberattack on Crimean internet providers,” noted Oleg Kryuchkov, an adviser to the Russian governor of the region, on Telegram.
“We are detecting interruptions in the internet on the peninsula,” he added. “All services are working to eliminate the threat.”
The outage has not been verified and it was not clear what could have caused it.
The missile attack comes a day after five people were killed when Russian missiles and artillery pounded cities across Ukraine.
Also on Thursday, Ukrainian President Volodymyr Zelenskyy met US President Joe Biden and congressional leaders in Washington.
Mr Biden has been pressing Congress to approve an extra aid package for Ukraine worth $24bn (£19.5bn) amid Russia’s ongoing invasion.
The Crimean Peninsula was annexed from Ukraine by Russia in 2014 in an act that most of the world saw as illegal.