Aug. 6 (UPI) — Ukraine said Thursday that it hit two oil refineries deep inside Russian territory in strikes overnight as well as tankers in Russia’s so-called shadow fleet and Russian naval vessels in the Black Sea. Six people were killed and 28 injured in Russian attacks on Ukraine’s Kharkiv, Sumy and Odessa regions.

Posting on X, Ukrainian President Volodymyr Zelensky said Ukraine Defense Forces carried out long-range drone attacks on the Bashneft-Novoil refinery 950 miles away in the Russian republic of Bashkortostan and the Slavneft-YANOS refinery, one of Russia’s largest, in Yaroslavl 270 miles northeast of Moscow.

Sharing footage of columns of black smoke rising into the sky amid the sound of explosions that the BBC said it had verified was of Yaroslavl, Zelensky said the actions were part of Ukraine’s strategy of targeting Russia’s ability to generate revenue from hydrocarbons, which in turn were used to fund the war.

“Today, our long-range sanctions once again worked to limit Russia’s oil revenues, which it uses to finance the war and the killing of Ukrainians. Our responses to Russian aggression in the Black Sea were also successful. In particular, two military patrol boats and shadow fleet vessels were struck,” wrote Zelensky.

In all, the latest attacks involved more than 600 drones.

Yaroslavl provincial Gov. Mikhail Evraev confirmed in an update on Telegram that four people were injured in what he called the largest ever attack on the region by enemy drones.

He said air defenses and electronic warfare units eliminated or disabled all 93 drones incoming, but that falling debris hit storage tanks at an oil refinery.

“Emergency services are working to extinguish the resulting fire. Falling debris also ignited three private homes, shattered windows in several apartment buildings, and damaged residents’ personal vehicles. The immediate threat to the region has passed,” he wrote.

Following one of the deadliest nights this year Wednesday when 17 people were killed and scores injured in the Kyiv region, Russia carried out more attacks overnight, killing three people and injuring five in a missile strike on a residential district of Balakliya, southeast of Kharkiv, Ukraine’s second-largest city, according to Kharkiv Gov. Oleh Syniehubov.

Writing on his Telegram account, Syniehubov said a separate drone strike on the rail station in Lozova, 85 miles south of Kharkiv, killed two men and injured five other men and three women.

A dozen people were injured in the northeastern city of Sumy and the southwestern port city of Odessa, one person was killed and three were injured in an attack on a bulk carrier vessel preparing to set sail with a cargo of wheat.