Ukrainian drones hit key Russian oil infrastructure on Sunday, including a key loading port in the Baltic Sea and two tankers that Ukraine alleged were used to illegally transport Russian crude oil, in violation of sanctions. They were among a wave of strikes targeting Russia's oil assets, on which Ukraine has focused its attacks recently.

A nighttime drone strike sparked a blaze at Russia's largest oil exporting port on the Baltic Sea, the port of Primorsk, according to Russian regional Gov. Alexander Drozdenko.

The port, operated by Russia's state oil firm Transneft, is capable of handling hundreds of thousands of barrels per day. Primorsk, which was targeted multiple times in March, lies over 620 miles from Ukraine, between the Russian-Finnish border and Russia's second-largest city of St. Petersburg.

Ukrainian drones have been striking Russian oil tankers increasingly often in recent weeks, as Ukraine seeks to diminish Russia's ability to export oil and offset Russia's financial gains since the war in Iran raised oil prices. Enforcing attacks on Russia's two main ports in the Baltic Sea, including Primorsk, have been the main targets of Ukrainian strikes. Together, the two ports account for around 40% of Russia's oil exports.

Local Gov. Drozdenko said that Sunday's drone strike did not cause an oil spill, but gave no immediate further comment regarding casualties or damage.

But Ukrainian President Volodymyr Zelenskyy said that Ukrainian forces destroyed several military and other targets, while also inflicting significant damage on oil port infrastructure.

"One more Russian carrier of Kalibr missiles is out of action. Major General Yevhen Khmara reported on the successful destruction of targets in the Primorsk port," Zelenskyy wrote in a Telegram post on Sunday.

According to Zelenskyy, Ukrainian drones also hit a Karakurt missile ship, a patrol boat, and a tanker belonging to Russia's so-called shadow oil fleet, used to evade Western sanctions and price caps on Russian energy.

In a separate post earlier on Sunday, Zelenskyy said that Ukrainian forces had struck two more "shadow fleet" tankers near the entrance of the Russian Black Sea port of Novorossiysk.

"These tankers were actively used to transport oil. Now they won't," he said. He added the operation was led by the chief of Ukraine's general staff, Andrii Hnatov.

Moscow did not immediately acknowledge Zelenskyy's claims regarding either strike.

Kyiv has recently stepped up its attacks on Russia's oil export infrastructure. Ukrainian officials argue that oil revenue directly funds Moscow's full-scale invasion of the country, now in its fifth year.

Elsewhere, two people were killed and three others wounded as Russian drones struck Ukraine's southern Odesa region overnight into Sunday, Ukraine's Emergency Service reported. It said the attack damaged three residential buildings.

The drones also hit port infrastructure, causing a fire that was later extinguished by emergency teams, the emergency service reported.

Nighttime Russian strikes also wounded six people in the Dnipropetrovsk region in central Ukraine, the agency said. A passenger bus transporting 40 children was damaged, but no one inside was injured, it added.

In Russia, a Ukrainian drone strike west of Moscow killed a 77-year-old man, local Gov. Andrei Vorobyov reported on the Telegram messenger app. He said the fatal attack occurred near the town of Volokolamsk, some 75 miles from central Moscow.

Vorobyov added that six drones were shot down in the Moscow region, which surrounds but does not include the Russian capital. At least five more drones were downed on the approach to Moscow itself, according to mayor Sergei Sobyanin.

Separately, in Russia's western Smolensk region, a man, woman and child were injured after Ukrainian drone debris flew into an apartment block, according to local Gov. Vasiliy Anokhin.

Russia's Defense Ministry reported on Sunday that a total of 334 Ukrainian UAVs were downed overnight over Russia and occupied Crimea.

Also overnight into Sunday, Russia attacked Ukraine with 269 drones and ballistic missiles, according to the Ukrainian Air Force. Ukrainian forces shot down and repelled 249 drones, while hits from ballistic missiles and 19 drones were recorded in 15 locations, the air force said in a Facebook update.