Grain fields burn on the outskirts of Kurakhove, Donetsk Oblast, eastern Ukraine, on Thursday. Nariman El-Mofty/Associated Press

KHARKIV, Ukraine — Russian shelling pounded a densely populated area in Ukraine’s second-largest city Thursday, killing at least three people and injuring at least 23 others with a barrage that struck a mosque, a medical facility and a shopping area, according to officials and witnesses.

Police in the northeast city of Kharkiv said cluster bombs hit Barabashovo market, where Associated Press journalists saw a woman crying over her dead husband’s body. Local officials said the shelling also struck a bus stop, a gym and a residential building.

The bombardment came after Russia on Wednesday reiterated its plans to seize territories beyond eastern Ukraine, where the Russian military has spent months trying to conquer the Donbas region, which is south of Kharkiv. It also followed Ukrainian attacks this week on a bridge the Russians have used to supply their forces in occupied areas near Ukraine’s southern Black Sea coast.

Kharkiv Mayor Ihor Terekhov said the attacks early Thursday targeted one of the most crowded areas of the city, which had a prewar population of about 1.4 million.

“The Russian army is randomly shelling Kharkiv, peaceful residential areas. Civilians are being killed,” Terekhov said.

At the market, Sabina Pogorelets’ desperate screams pierced the air as she begged Ukrainian police to let her embrace her husband, Adam, a vendor whose body was lying partly covered with cloth next to a small stall. A bloody wound could be seen on his head as policemen gently pulled his wife away so medical workers could take away his body.

“Please! I need to hold his hand!” Pogorelets cried.

Nearby, a man hugged his small daughter as he and other visitors stood in shock. Emergency teams treated at least two of the wounded in nearby ambulances.

“People started working little by little, they came out to sell things, and residents came here to buy things,” said Volodymyr Tymoshko, head of the National Police in the Kharkiv region. “And exactly this place was hit by Uragan rockets with cluster bombs to maximize the damage to people.”

The cluster bombs claim could not be independently confirmed. AP journalists at the scene saw burned-out cars and a bus pierced by shrapnel.

The Kharkiv regional governor, Oleh Syniehubov, said four people were in grave condition and a child was among those wounded in the shelling. Russian forces also shelled wheat fields, setting them on fire, he said.

Elsewhere, Russian forces shelled the southern city of Mykolaiv overnight as well as the eastern cities of Kramatorsk and Kostiantynivka, where two schools were destroyed, Ukrainian officials said. A man’s body was recovered from the rubble of the school in Kramatorsk, and emergency workers say two more people were feared trapped there.

The scattered attacks illustrate broader war aims beyond Russia’s previously declared focus on the Donbas region’s Donetsk and Luhansk provinces, which pro-Moscow separatists have partly controlled since 2014.

Foreign Minister Sergey Lavrov told Russian news outlets on Wednesday that Russia plans to retain control over more territory, including the Kherson and Zaporizhzhia regions in southern Ukraine. Moscow also envisions making gains elsewhere, Lavrov said.

Analysts from the Institute for the Study of War, a think tank based in Washington, said the Russian offensive in Donetsk was likely to stall before reaching the cities of Sloviansk and Bakhmut. “Russian troops are now struggling to move across relatively sparsely settled and open terrain. They will encounter terrain much more conducive to the Ukrainian defenders,” their assessment said.

Richard Moore, head of the British foreign intelligence agency MI6, had a similar take, saying the Russians “are about to run out of steam” in Ukraine.

“They will have to pause in some way, and that will give the Ukrainians opportunities to strike back,” Moore said.

He said it is important for Ukraine to demonstrate its ability to respond militarily to Russia, both to maintain morale and as “an important reminder to the rest of Europe that this is a winnable campaign by the Ukrainians because we are about to go into a pretty tough winter.”

Ukraine’s military reported Thursday that Russian forces attempted to storm the Vuhlehirska power station in the Donetsk region, but said “Ukrainian defenders made the enemy resort to fleeing.”

In other developments Thursday:

• The operator of a major pipeline from Russia to Europe says natural gas has started flowing again after a 10-day shutdown for maintenance. But the gas flow was well short of full capacity and the outlook was uncertain. The Nord Stream 1 pipeline to Germany had been closed since July 11 for annual maintenance. The pipeline is Germany’s main source of Russian gas. German officials had feared that the pipeline might not reopen at all amid growing tensions over Russia’s war in Ukraine.

• Turkish officials said a deal on a U.N. plan to unblock the exports of Ukrainian grain and to allow Russia to export grain and fertilizers will be signed Friday in Istanbul. Turkish President Recep Tayyip Erdogan’s office said that he, U.N. Secretary General Antonio Guterres, and officials from Russia and Ukraine will oversee the signing ceremony. Guterres has been working on a plan to enable the export of millions of tons of grain stockpiles that have been stuck in Ukraine’s Black Sea ports due to the war. The move could ease a global food crisis that has sent wheat and other grain prices soaring. Kremlin spokesman Dmitry Peskov declined to comment.

• Ukraine’s nuclear energy plant operator says Russian forces have placed explosives and weapons in parts of the Zaporizhzhia nuclear plant where they pose significant danger. Energoatom said the heavy weapons and explosives are in the building that houses one of six reactors at Europe’s largest nuclear power station. “They are continuing to cynically, absolutely violate all norms and demands of fire, nuclear and radiation safety,” the statement said.

• Lavrov, Russia’s foreign minister, said Moscow will consider boosting natural gas supplies to Hungary following a formal request from Budapest. He spoke after a meeting in Moscow with Hungarian Foreign Minister Péter Szijjártó. Russian news agencies say Szijjártó sought to get an additional 700 million cubic meters of gas from Russia this year.

• Russia barred 39 representatives of Australian security services and defense companies from entering the country, in response to sanctions imposed by Canberra earlier this year.