The drone strike on Sunday morning targeted Russia's Black Sea Fleet HQ on Fleet Day, an annual celebration of the Russian navy.
A drone attack on the headquarters of Russia's Black Sea Fleet, as Russia celebrated Fleet Day, has left five people injured.
The strike happened on Sunday morning in Sevastopol, a Ukrainian city which was annexed by Russia.
"This morning Ukrainian nationalists decided to spoil the Russian Fleet Day" celebrated in Russia on Sunday, the governor of Sevastopol wrote on social media.
He said a drone landed in the yard of the Fleet Headquarters and exploded, injuring five staff people.
All festivities related to the Russian Fleet Day "have been cancelled for security reasons", the governor said.
Large-scale celebrations are planned for the holiday across Russia, including a naval parade in the northwestern city of St Petersburg, to be supervised by President Vladimir Putin.
Zelenskyy orders Donetsk region evacuation
The drone strike on Sevastopol came just hours after Ukrainian President Volodymyr Zelensky called for civilians to evacuate the Donetsk region to escape "Russian terror."
"A government decision has been made on the mandatory evacuation of the Donetsk region," Zelensky said in a video address on Saturday evening. "Please evacuate," he demanded. "The more people leave the Donetsk region now, the fewer people the Russian army will kill."
"At this stage of the war, terror is Russia's main weapon," he said.
Ukrainian Deputy Prime Minister Iryna Verechtchuk had earlier announced the mandatory evacuation of the entire population of Donetsk, one of two administrative regions in the Donbass industrial basin where Russia is gaining ground.
She had justified this decision, in statements on television, by the destruction of the gas networks and the absence of heating next winter in the region.
At least 200,000 civilians still live in the territories of the Donetsk region that are not under Russian occupation, according to an estimate by the Ukrainian authorities.
"In total, there are currently about 52,000 children in the Donetsk region. Police officers are explaining to parents that the evacuation involves providing accommodation and all necessary assistance," said the state police, which is in charge of the operation.
Russian strikes on the region's cities are claiming civilian lives almost daily. On Saturday night, the Ukrainian army reported Russian artillery strikes in Bakhmut and Kramatorsk, near the front line.
On the southern front, on Saturday night, the town of Mykolayev was heavily shelled, "probably the heaviest ever", according to its mayor. "Powerful explosions were heard between 1am and 5am. Residential buildings were damaged. Several fires broke out at the affected sites," Oleksandr Senkevych said on Telegram.