Ukraine launched a new wave of attacks inside Russian territory on Sunday, killing at least two people, one of them a teenager, according to local officials, while Russians cast their votes on the final day of the presidential election, which is set to extend President Vladimir Putin's rule for another six years.

Authorities also said a drone crashed into a refinery in the Krasnodar region, causing a fire that was extinguished after a few hours. Officials said one refinery worker died of a heart attack.

Refineries and oil stations have been targets of Ukrainian drone attacks in recent days, according to Russian officials, as part of increasing attacks on Russian territory, including long-range drone attacks and alleged incursions by Russian agents based in Ukraine, while Putin heads toward his second re-election in Russia.

The Russian Defense Ministry announced that it shot down 35 Ukrainian drones overnight, including four in the Moscow region. Moscow Mayor Sergey Sobyanin said a fifth drone near Domodedovo Airport in the capital was shot down Sunday morning. No injuries or damages were reported.

According to the Defense Ministry, two drones were shot down over the Kaluga region, south of the Russian capital, and four in the Yaroslavl region, northeast of Moscow.

The attacks on the Yaroslavl region, located about 800 kilometers (500 miles) from the Ukrainian border, were among the furthest attacks Ukraine has launched so far.

The Defense Ministry said more Ukrainian drones were shot down over the Belgorod, Kursk, and Rostov regions bordering Ukraine and the southern Krasnodar region.

Governor Vyacheslav Gladkov said the shelling of Belgorod on Sunday morning killed a 16-year-old girl and injured her father, while a second attack later in the day killed another man and injured 11 others.

Elsewhere, officials said a drone strike on a military facility in the breakaway Transnistria Republic in Moldova on Sunday destroyed a helicopter and caused a fire. Russia-aligned authorities in the area blamed Ukraine for the attack. The Reintegration Policy Office said in a statement that it "does not confirm any attack" on Transnistria, describing the reports as "an attempt to incite fear and panic in the region."

The past few days have seen a series of Ukrainian drone raids described by Putin as an attempt by Ukraine to intimidate the population and disrupt the Russian presidential election.

He pledged during a Russian Security Council meeting on Friday that "these enemy strikes will not and have not gone unpunished." He added, "I am sure our people, the people of Russia, will respond with greater unity."

Two Russian ballistic missiles struck the city of Mykolaiv in southern Ukraine on Sunday, injuring at least five people, regional governor Vitaliy Kim wrote on the messaging app Telegram.

The Ukrainian military also said it shot down 14 Russian drones over the Odessa region on Sunday, following a Russian ballistic missile attack on the southern coastal city on Friday that killed at least 21 people.

The British Defense Ministry announced on Sunday that Defense Secretary Grant Shapps canceled a trip to Odessa earlier this month due to a Russian missile threat. The Sunday Times reported that Shapps, who visited Kyiv on March 7, received a warning from British intelligence that Russia had become aware of his travel plans.

As the war enters its third year, Russian forces have made some slow and gradual gains along the front line, relying on their superiority in firepower, while Ukraine responded with more drone attacks deep inside Russia.

There have also been an increasing number of cross-border raids.

The Russian Freedom Legion, one of the armed groups composed of Russians fighting alongside Ukrainian forces, announced on Sunday that it had taken control of the border village of Gorkovsky in the Belgorod region. A video clip posted on social media shows troops removing the Russian flag from the village’s main administrative building. The images have not been independently verified by The Associated Press.

A similar group, the Russian Volunteer Legion, posted a video on social media on Saturday claiming to have captured 25 Russian soldiers. This claim also cannot be independently verified.

Meanwhile, the Russian military said on Saturday it thwarted another attempted border incursion by Ukrainian "sabotage and reconnaissance groups."

Cross-border attacks have occurred sporadically in the region since the war began and have been the subject of claims and counterclaims as well as misinformation and propaganda.