A drone hit a busy beach in southern Russia, killing seven people including three children, local authorities have said.

In social media footage verified by the BBC, a drone can be seen hurtling towards a cliffside before crashing into a fireball on the beach below as tourists look on from the shore and in the water.

The total number of injured reached 40, with 17 people hospitalised, said the governor of the Krasnodar region Veniamin Kondratyev.

He accused Ukraine of “a deliberate strike on civilians”. Ukraine has not commented. Both sides deny targeting civilians deliberately.

It is unclear what the drone was targeting. Some Ukrainian Telegram channels have claimed it crashed onto the beach as a result of electronic warfare which jammed the drone’s signal. Several eyewitnesses were quoted by Russian media as saying gunfire preceded the explosion, indicating that air defences may have tried to shoot the drone down.

The crash occurred on a beach near the village of Arkhipo-Osipovka on the Black Sea. With its warm climate, long beaches and developed tourist infrastructure it is a popular holiday destination for Russians, in particular since sanctions have curtailed international travel for many.

Tourists and residents of Arkhipo-Osipovka told local media outlets that no sirens sounded ahead of the drone attack.

“We covered ourselves with sun loungers, and didn’t see where it exploded,” said one holidaymaker. Another person said that while they did not see the drone hit they could hear “gunfire, like a machine gun” followed by an explosion.

“This all happened in front of my children. My child is having a nervous breakdown,” said a third.

Over the course of the last year Ukraine has had increasing success in carrying out long-range strikes deep into Russia, hitting energy infrastructure and commercial warehouses it says are used for military purposes.

On several occasions these strikes have caused civilian deaths, with eight people in different Russian cities killed at the weekend.

Russia meanwhile has launched attacks on residential areas and cities from the start of its full-scale invasion of Ukraine in February 2022, killing and injuring thousands of civilians.

On Saturday, at least nine people were killed and dozens injured in Russian ballistic missile strikes on Kyiv, according to Ukrainian President Volodymyr Zelensky. The city’s mayor said a residential building in the Shevchenkivskyi district was partially destroyed, trapping people inside. Last week a strike on a building in Ukraine’s Kryvyi Rih area killed a family of 10.

In recent weeks Ukrainian strikes have in particular targeted warehouses belonging to Wildberries – a large online retailer dubbed the “Russian Amazon”.

The latest strike hit a warehouse in the Vladimir region, east of Moscow, overnight into Monday. Dozens of Wildberries warehouses dotted around Russia – many located thousands of kilometres from the Ukrainian border – have now been hit.

Kyiv says Wildberries depots are used to supply the Russian military, which Moscow denies. Yet the platform sold a variety of military-related goods such as body armour until recently, alongside items with both civilian and drone-production applications.