A man inspects a damaged car at the site of a Russian strike in the city of Sumy, August, 2024, amid the Russian invasion of Ukraine .AFP
Videos published on social media showed thick black smoke and bursts of flames coming from the site of the blaze, which the governor said was in the town of Proletarsk.
"In the south-east of the Rostov region, air defences repelled a drone attack. As a result of falling debris on the territory of industrial storage facilities in Proletarsk, a diesel fuel fire broke out," Governor Vasily Golubev said on Telegram.
"At 05:35 (0235 GMT), firefighting at the industrial facility in Proletarsk was suspended due to a second drone attack," he added in an update to the post.
No-one was injured and firefighting efforts resumed shortly after, he said in a later post.
Proletarsk is some 250 kilometres (155 miles) from the Ukrainian border and some 350 kilometres from Kyiv-held areas of fighting on the eastern Ukrainian frontline.
The Russian defence ministry said it shot down five "aircraft-type" Ukrainian drones overnight, including two over the Rostov region.
Kyiv has repeatedly targeted oil and gas facilities in Russia since the conflict began in 2022, some hundreds of kilometres from its borders, in what it has called "fair" retaliation for attacks on its energy infrastructure.
Earlier this month, Ukrainian President Volodymyr Zelensky praised his forces for hitting oil facilities in Russia, saying the attacks would help bring a "just end" to the conflict.
The drone attacks come as Ukraine mounts an unprecedented cross-border assault into Russia's Kursk region, where it claims to control more than 80 settlements.
Meanwhile, Ukrainian forces said they thwarted a Russian missile attack on the capital Kyiv where air raid sirens sounded dawn n on Sunday.
"This is the third ballistic missile attack on the capital in August with a clear interval of six days between each attack," the Kyiv City Military Administration posted on Telegram after the early morning barrage.
Simultaneous to the missile attack, drones were spotted heading to Kyiv.
"All enemy drones were destroyed far outside the city," it added.
No damage or casualties were reported from the attack, which the administration said had "most likely used North Korean ballistic missiles of the KN-23 type".
The United States and Seoul have accused North Korea of providing ammunition and missiles to Russia for its war in Ukraine.
Kyiv has repeatedly called for its allies in the West to provide more air-defence systems.
On Saturday, Ukrainian President said that his army was reinforcing its positions in the Russian region of Kursk with the operation "proceeding exactly as we expected".
On the other side of the front line, Russian air defences destroyed five Ukrainian drones in the Belgorod, Kursk and Rostov regions on Saturday night, the Russian Defence Ministry said.
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