Explosions rocked the southern Ukrainian city of Mykolaiv on Saturday, the mayor said, at the end of a week in which Russian missiles have slammed into an apartment block and a shopping mall in other cities, killing dozens of people.
Air raid sirens sounded in the Mykolaiv region, which borders the vital Black Sea port of Odesa.
"There are powerful explosions in the city! Stay in shelters!" Mykolaiv mayor Oleksandr Senkevych wrote on the Telegram messaging app.
The cause of the blasts was not immediately clear, although Russia said on Saturday it had hit army command posts in the area. Reuters could not independently verify the reports.
Kyiv says Moscow has intensified missile attacks on targets far from the frontline and that it has deliberately hit civilian sites while Russian forces have been grinding out gains on the battlefield in the east, pummelling urban areas with artillery.
Russia says it has been aiming at military sites and denies taking aim at civilians. Kremlin spokesperson Dmitry Peskov said, "Russian Armed Forces do not work with civilian targets".
An apartment block was partly flattened in Odesa on Friday, which the authorities said killed at least 21 people, after Monday's strike on a shopping mall in the central city of Kremenchuk that officials said left at least 19 dead.
Ukrainian President Volodymyr Zelenskyy denounced the strikes in his nightly video address on Friday as "conscious, deliberately targeted Russian terror and not some sort of error or a coincidental missile strike".
Russia's defense ministry said on Saturday it had destroyed Ukrainian army posts in Mykolaiv and the eastern Donbas region with high-precision weapons and hit other military-related sites in the southern Zaporizhzhia region and Kharkiv to the north, Russian news agencies reported.
Thousands of civilians have been killed since Russia invaded Ukraine on Feb. 24 in what Moscow calls a "special military operation" to root out nationalists. Ukraine and its Western allies say it is an unprovoked war of aggression.
Residents in the resort village of Serhiivka near Odesa helped workers pick through the rubble of the nine-story apartment block, part of which was destroyed in Friday's strike.
"We came here to the site, assessed the situation together with emergency workers and locals, and together helped those who survived. And those who unfortunately died. We helped to carry them away," said Oleksandr Abramov, who lives nearby.
The region will observe a day of mourning on Saturday.
The Serhiivka strike came shortly after Russia withdrew from Snake Island, a strategic Black Sea outcrop about 140 km (85 miles) southeast of Odesa seized on the first day of the war.
Russia had used Snake Island to impose a blockade on Ukraine, one of the world's biggest grain exporters and a major producer of seed for vegetable oils. The disruptions have helped fuel a surge in global grain and food prices.
Russia, also a big grain producer, denies it has caused the food crisis, blaming Western sanctions for hurting its exports.
Putin met Indonesia's president on Thursday and spoke by phone on Friday to the prime minister of India, promising both major food importers that Russia would continue supplying grain.
As missiles have struck Ukrainian cities, Russian forces in the east have slowly advanced on the ground, raining down shells on Ukrainian forces battling to hold urban centers. Moscow aims to drive Ukraine out of Luhansk and Donetsk provinces, which make up the industrial region known as Donbas.
Moscow has been on the verge of capturing Luhansk province since taking the city of Sievierodonetsk last week after some of the heaviest fighting of the war.
Ukraine's last bastion in Luhansk is Lysychansk, which is close to being encircled under Russian artillery barrages.
"Private houses in attacked villages are burning down one by one," Luhansk Governor Serhiy Gaidai said on Telegram, adding that shelling stopped Lysychansk residents from dousing fires.
The governor of Donetsk region said four civilians were killed by shelling on Friday and 12 injured.
Ukraine's military reported widespread Russian shelling on Friday, including on Kharkiv in the north and on Ukrainian positions in the border areas of Sumy and Chernihiv.
Zelenskyy said more weapons were needed in eastern and southern Ukraine. The United States said it was sending two NASAMS surface-to-air missile systems, four additional counter-artillery radars and ammunition in its latest shipment.