Ukraine says the southern city of Mykolaiv suffered “massive” Russian bombardment overnight.
Authorities said one person was killed, while the mayor said the shelling was “probably the strongest of all time”.
There was damage to a hotel, a sports complex, two schools and a service station, as well as homes. Mykolaiv is on the main route to Odesa, Ukraine’s main port, and has been hit repeatedly.
Meanwhile, Russia has cancelled Navy Day celebrations in occupied Crimea.
The reason given by Sevastopol Governor Mikhail Razvozhayev was an alleged Ukrainian drone strike on the Black Sea Fleet headquarters. The fleet has long been based in Sevastopol.
But a senior Ukrainian official, Serhiy Bratchuk, dismissed the Russian report as a “provocation”. “The liberation of our Crimea will take place differently and much more efficiently,” he said.
Russian forces annexed Crimea in 2014. That was internationally condemned as illegal and triggered sanctions against Russia.
Navy Day is an annual Russian holiday, and celebrations are taking place across Russia on Sunday. President Vladimir Putin will oversee events in St Petersburg, his home city.
In a Telegram post, the Sevastopol governor said “an unidentified object flew into the courtyard of the [Black Sea] Fleet headquarters” and “according to preliminary data, it was a drone”.
Blaming “Ukronazis”, he said six people – Fleet HQ staff – were wounded, and none were killed.
Russia has often accused Ukrainian authorities of being “Nazis”, as part of the Kremlin’s propaganda campaign to justify its invasion of Ukraine on 24 February 2022.
A photo posted by Governor Razvozhayev showed him in a courtyard littered with leaves, but with no obvious structural damage. He said the Navy Day celebrations had been cancelled for security reasons.
In a previous blow to the Black Sea Fleet, in April, the fleet’s flagship Moskva sank after what Ukraine described as a strike with two Neptune missiles.
Russia admitted there was a big fire on board caused by exploding ammunition, without attributing it to a Ukrainian attack, and said the missile cruiser sank in a storm while being towed.
It remains unclear how many Russian sailors were killed or injured in the ship’s demise.
Meanwhile in the north, Ukraine’s second city Kharkiv was hit by Russian missiles again, mayor Igor Terekhov said on Telegram. Three Russian S-300 missiles struck a school there, destroying the main building, he said.
The BBC was unable to verify the latest reports independently.
In a late-night address on Saturday, Ukraine’s President Volodymyr Zelensky told all civilians still living in parts of eastern Donetsk region under Ukrainian control to evacuate.
The region has seen heavy clashes amid a slow advance by Russian forces, who already control large parts of it.
“The more people leave Donetsk region now, the fewer people the Russian army will have time to kill,” Mr Zelensky said. “We will use all available opportunities to save as many lives as possible and to limit Russian terror as much as possible.”
It is not the first time the Ukrainian authorities have told people to leave the area. An evacuation notice from the government warned the coming winter would make thing worse, especially for children.
“They need to be evacuated, you cannot put them in mortal danger in the winter without heating, light, without the ability to keep them warm,” Kyiv’s Ministry of Reintegration of Temporarily Occupied Territories said.
Also in Donetsk, Russia claims it has invited UN and Red Cross officials to investigate the deaths of 50 Ukrainian prisoners of war (POWs) in part of the region held by Russian-backed separatists.
The troops were killed during an attack which wrecked a prison in Olenivka. Russia and Ukraine blamed each other for it.