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.