A state of emergency has been declared in the Russian city of Engels after a Ukrainian drone strike hit an oil depot that supplies Russia's nuclear bomber planes.
Saratov regional governor Roman Busargin said that two firefighters had been killed while tackling the blaze.
A huge fire exploded at the “Kristal” oil complex, as well as multiple explosions, in the city of Engels after long-range strikes, said Ukraine’s military.
It added that the oil depot supplied fuel to the “Engels-2” military airfield, where Russia’s nuclear bomber fleet is based.
“The strike of the oil depot creates serious logistical problems for the strategic aviation of the Russian occupiers and significantly reduces their ability to strike at peaceful Ukrainian cities and civilian objects,” the Ukrainian military said.
Russian news reports said the fire was at an oil facility.
Unverified videos and photos published on social media showed a large fire burning with orange flames, sending thick clouds of smoke into the night sky.
Mr Busargin said the cities of Saratov and Engels, on opposite sides of the Volga river, had been subject to a “mass drone attack” and there was a fire at an industrial site, but that there were no known casualties.
“There are sufficient forces and resources to localise the fire,” he added.
Russia’s defence ministry said in a statement that 11 Ukrainian drones had been destroyed overnight over the Saratov region, and 21 over other parts of Russia and the Azov Sea.
The Engels air base is located about 450 miles southeast of Moscow and hundreds of miles from the Ukrainian border.
In December 2022, three Russian air force personnel were killed when a drone was shot down there.
The Ukrainian military said on Wednesday that Russia launched a total of 64 drones at the country overnight.
Of those drones, Ukraine’s air force shot down 41, while 22 “imitator drones” did not reach their targets, the air force added.
The use of drones in Vladimir Putin’s war has spiralled, with military experts saying they now may have more impact on the battlefield than soldiers.
Both the Ukraine capital Kyiv and Moscow have come under drone attacks.
In eastern Ukraine, Russian forces continued to seize more land.
“Russian forces recently advanced in northwestern Toretsk (Donetsk province) following several weeks of higher-tempo Russian offensive operations and gains in the area,” said the Institute for the Study of War.
Thousands of North Korean troops have been sent to join the Russian bid to seize back Kursk but they have suffered heavy casualties.
