Russian forces pounded Ukraine’s second largest city Kharkiv and surrounding countryside with rockets, killing at least 20 people in what Kyiv called a bid to force it to pull resources from the main battlefield to protect civilians from attack.

Inside Russia, a fire tore through an oil refinery just 8km from the Ukrainian border, after what the refinery described as a cross border attack by two drones.

In the main battlefield city of Sievierodonetsk, where Russia has claimed to have Ukrainian forces surrounded since last week, scenes filmed by a freelance journalist made clear the battle was not over, with Ukrainian troops able to re-supply their garrison by crossing a river in inflatable rafts.

The Russian strikes on Kharkiv, throughout Tuesday and continuing on Wednesday morning, were the worst for weeks in the area where normal life had been returning since Ukraine pushed Russian forces back in a major counter-offensive last month.

“It was shelling by Russian troops. It was probably multiple rocket launchers. And it’s the missile impact, it’s all the missile impact,” Kharkiv prosecutor Mikhailo Martosh told Reuters amid the ruins of cottages struck on Tuesday in a rural area on the city’s outskirts.

Medical workers carried the body of an elderly woman out of the rubble of a burnt-out garage and into a nearby van.

“She was 85 years old. A child of the war (World War II). She survived one war, but didn’t make it through this one,” said her grandson Mykyta.

“There is nowhere to flee to. Especially grandmother herself, she didn’t want to go anywhere from here.”

Ukrainian authorities said 15 people were killed and 16 wounded on Tuesday in the Kharkiv region.