A Russian soldier in Crimea, the Black Sea peninsula illegally annexed by Russia, opened fire on his colleagues, ​killing ‌one and wounding ⁠another, before turning his weapon on ‌civilians and killing three, an official said ⁠on Tuesday.

Three other people were wounded, said Mikhail ​Razvozhayev, the Russian-installed governor of ‌the Sevastopol region. He said the attacker had been arrested.

There ‌was no information on the motive ​for the attacks.

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“All circumstances and causes of the incident are ​being established,” said Razvozhayev, urging ​people to remain calm ​and not to spread rumours.

The shooting comes as an uptick of civilian casualties is reported in Crimea and along Russian shores on the Black Sea. 

Four people were killed in a Ukrainian strike on Russia-annexed Crimea, the Moscow-installed governor Sergey Aksyonov said Monday in a post on Telegram.

Unverified social media footage also showed what appeared to be a drone crashing into a busy beach at the Russian resort of Arkhipo-Osipovka, on the Russian Black Sea coast east of Crimea, as tourists looked on from the shore and in the water.

Russian officials said six people were killed there, including several children.

“The number of people killed in the village of Arkhipo-Osipovka has risen to six, three of them children,” Venyamin Kondratyev, the governor of the Krasnodar region, said on social media, after earlier announcing Ukraine had struck the area in a drone attack.

The Black Sea coast and Crimea are both summer destinations popular among Russian tourists.

Ukraine often fires hundreds of drones into Russia at night, in retaliation for Moscow’s own barrages of drones and missiles against Ukrainian towns and cities.

(FRANCE 24 with Reuters, AFP)