KREMENCHUK, Ukraine – As rescuers scoured the rubble of a destroyed shopping center in central Ukraine on Tuesday morning, the death toll from a Russian missile strike the previous day rose to 18, the mayor of the city.

Fifty-nine people remained injured and 36 others are still missing, Vitaliy Maletskiy, the mayor, wrote on Facebook. Hundreds of people were inside the mall.

Ukraine’s chief prosecutor, Irina Venediktova, arrived at the scene on Tuesday with a team of investigators to gather evidence into what she said constituted both a “war crime” under Ukrainian law and a crime against humanity.

About 60 people had requested medical help, the mayor said. At a hospital where the injured were being treated, five people were in critical condition, according to chief medical officer Oksana Korlyakova.

The prosecutor denounced what she described as the “systematic shelling of civilian infrastructure: hospitals, nurseries, shopping centers as you see here”.

“I’m sure the Russians know very well that they are killing civilians,” Ms Venediktova added. “For them it’s nothing new, but they do it again and again.”

The Russian Defense Ministry admitted in a statement on Tuesday to hitting Kremenchuk with what it described as high-precision missiles. But he said the mall was set on fire by an explosion at its main target, which he said were depots containing ammunition for weapon systems supplied by the United States and European countries.

The claims could not be independently verified, and Ukraine’s interior minister said in a briefing for reporters on Tuesday that “there is no military object within five kilometres”.

In a small park next to the shopping center, an improvised memorial of 16 vases filled with flowers had been installed. Grim visitors lit candles for the dead.

Ukrainian President Volodymyr Zelensky said in an evening video address that the strike was intentional. “It’s not an accidental hit – it’s a calculated Russian strike,” he said.

It was the sixth and deadliest Russian missile strike on Kremenchuk, an industrial city that had a population of 217,000 before the war. Although some residents have left, many displaced people have also arrived from places further east that have suffered heavy shelling, such as Kharkiv and Mariupol.

Among those injured in Monday’s strike was Yulia, 22, who fled from Kharkiv to Kremenchuk with her mother. They previously lived in Luhansk, a city occupied by Moscow-backed separatists in 2014.

Yulia and her mother, Larisa, had fled to Kharkiv after the first fighting, then two months ago they fled again to Kremenchuk because of heavy shelling in Kharkiv. She had found a job selling cell phones in the mall.

“We hoped we would be safe here,” said Larisa, who didn’t feel comfortable sharing her last name. “It’s a deep trauma to my soul.”

In the hours following the strike, pro-Moscow news outlets and social media quickly dismissed the Ukrainian staged attack.

“I want the world to know that’s not wrong,” Larisa said. “People have suffered, and it’s very scary.”

Ivan Nechepurenko contributed reporting from Tbilisi, Georgia.