KYIV (AFP) — More than 4,000 people have been evacuated from border areas in Ukraine’s northeastern Kharkiv region, the local governor said on Sunday, following a surprise cross-border Russian offensive there that began on Friday.

“In total, 4,073 people have been evacuated,” governor Oleg Synegubov wrote on social media, a day after Russian forces claimed the capture of five villages in the region.

Synegubov said that on Sunday a 63-year-old man was killed by artillery fire in the village of Glyboke and a 38-year-old man was wounded in Vovchansk, a border town with some 3,000 residents before the current offensive.

Ukraine on Friday announced that Russia had launched an attack in the Kharkiv region, making small advances into a border zone from where it had been pushed back nearly two years ago.

President Volodymyr Zelensky said on Saturday that Ukrainian troops had been carrying out counterattacks in border villages in Kharkiv region.

“Disrupting Russian offensive plans is now our number one task,” he said.

Troops must “return the initiative to Ukraine,” the president insisted, again urging allies to speed up arms deliveries.

Ukrainian officials had warned for weeks that Moscow might try to attack its northeastern border regions, pressing its advantage as Ukraine struggles with delays in Western aid and manpower shortages.

Refinery set ablaze

Meanwhile, a Ukrainian drone attack hit a refinery in Russia’s Volgograd region causing a fire at the complex, the regional governor said Sunday.

Russia’s defense ministry said eight overnight drone attacks were intercepted, including one in the southern Volgograd region.

“During the night of 12 May the air defense and electronic warfare forces fought off a drone on the territory of the Volgograd region,” Governor Andrey Bocharov wrote on Telegram.

“The consequences from the fall of a drone followed by a detonation caused a fire on the site of the Volgograd oil refinery,” he added.

Bocharov said the fire had been put out and there were no victims.

Owned by Lukoil, the Volgograd refinery says on its website that it is the biggest producer of oil products in southwest Russia.

It was the target of a Ukrainian attack in February, when authorities also said there were no victims.

Ukraine has intensified its drone attacks this year as it seeks to overcome a shortage of military equipment and manpower more than two years since Russia launched the military offensive against its neighbor.

As Ukrainian forces up attacks inside Russia and on Russia-held areas of Ukraine, energy facilities have been a key target.

Ukraine says the attacks are in response to Russia’s targeting of civilians.