A drone exploded at a beach near the Black Sea village of Arkhipo-Osipovka in Russia’s Krasnodar region, killing seven people, including three children, regional authorities said.
Governor Veniamin Kondratyev said 40 people were injured and 17 of them were admitted to hospital.
Footage circulating on social media showed a drone flying toward a steep hillside before exploding beside the beach.
Kondratyev blamed Ukraine and described the incident as an intentional attack on civilians.
Ukraine had not issued a public comment on the accusation at the time of publication.
It remains unclear whether the beach was the drone’s intended target.
Several Ukrainian Telegram channels claimed that electronic jamming caused the drone to lose control and crash.
Some witnesses said they heard gunfire before the explosion, raising the possibility that Russian air defences had tried to bring down the drone.
Local residents and tourists said no warning siren was heard before the blast.
The area is a popular domestic holiday destination on Russia’s Black Sea coast.
Ukraine has stepped up long-range strikes inside Russia over the past year and says it targets energy facilities and warehouses used for military purposes.
Both Russia and Ukraine have repeatedly denied deliberately targeting civilians during the war.
Ukrainian President Volodymyr Zelenskyy said a Russian ballistic-missile strike on Kyiv on Saturday killed nine people and injured others.