As Russia renews shelling in Kharkiv, the civilian death toll is growing, officials say.

While fierce battles continue for the Donbas region in Ukraine’s east amid warnings of a Ukrainian counteroffensive in the south, Russian shelling in and around Kharkiv, Ukraine’s second-largest city, in the northeast of the country, has grown more intense in recent days.

Fifteen civilians were killed and 16 were wounded in Kharkiv during daytime shelling, Oleg Sinegubov, the head of the Kharkiv regional administration, said on Tuesday. Russian forces were firing “en masse on residential areas in Kharkiv,” he said on Telegram.

“The occupiers are deliberately beating residential areas where there are no military facilities,” he said. “This is real terrorism against civilians.”

The civilian death toll included an 8-year-old girl from the village of Bezruky. In the Kharkiv region alone, 43 children have been killed by Russian forces and 130 have been injured, according to Mr. Sinegubov’s post. Kharkiv’s mayor, Ihor Terekhov, said this week that shelling had grown worse in the city, which was being hit “night, morning, day.”

In his nightly address to the nation, President Volodymyr Zelensky of Ukraine referred to the shelling. It simply destroys, simply kills,” he said, adding that, “the Russian army is deaf to any rationality.”

Last month, Ukrainian troops appeared to have pushed Russian forces back from the city, even as far as the border, about 25 miles away. But Russia does not appear to have given up on its efforts around the city, using railway lines around Kharkiv to supply troops that appear to be preparing for an assault on the city of Sloviansk, according to the Institute for the Study of War, a research group based in Washington.

Russian forces may also be trying to keep their opponents occupied and spread out along the vast front line, reducing Ukraine’s ability to concentrate on the fight for Sievierodonetsk, a focal point of the eastern front, or on the counteroffensive in the southern Kherson region.

The Russian military’s struggles in Ukraine have led to the replacement of its commander of airborne forces, Andrey Serdyukov, according to the Institute for the Study of War, which cited the Russian news media. In its latest assessment, the institute said Moscow might be “in the process of radically reshuffling the command structure of the Russian invasion of Ukraine, indicating a possible purge of senior officers blamed for failures in Ukraine.”

In eastern Luhansk, the number of civilians injured and killed by overnight Russian shelling is yet to be determined, Serhiy Haidai, the region’s military governor, said on Facebook. “The shelling lasted through the night and all of yesterday,” he said. “More than 10 multistory buildings, private houses and the police department building were destroyed.”

Last week, Amnesty International issued a report accusing Russian forces of launching “a relentless campaign of indiscriminate bombardments against Kharkiv.” In May, the United Nations’ International Organization for Migration estimated that 23 percent of the more than eight million Ukrainians who have fled to other parts of the country were from the Kharkiv region.