Claims of casualties were made by the Russian-installed city administration and could not be immediately verified, although footage on social media showed a large explosion lighting up the night, burning ammunition and smoke. The blast hit a warehouse near a key railway line and a dam on the Dnipro River. Images from Nasa Firms Global Fire Monitoring System showed a series of secondary fires in buildings around the original blast site. Pro-Russian officials and some Ukrainian commentators were quick to suggest that the explosion was the result of a strike by Ukraine’s newly-supplied US Himars missile system. Several recent strikes on ammunition depots and Russian command centers have been attributed to Kheimari. Map of Ukraine Russian administration officials said the attack destroyed warehouses containing salts, a chemical compound that can be used to make fertilizers or gunpowder. In the Donetsk region, Ukraine’s state emergency service continued to search for survivors of a Russian attack on an apartment building in Chasiv Yar, where the death toll reached 34. According to rescuers, the last body recovered was that of a child. Emergency services continue to search for five survivors trapped under the collapsed five-story building. The overnight strike in Nova Kakhovka was the fourth time in recent days that Ukraine has hit warehouses in the city. There are expectations of a widespread Ukrainian counteroffensive in the south, and some analysts have suggested that Ukraine had now destroyed both major Russian weapons depots serving the city of Kherson. Russian forces largely occupy Kherson province, which is adjacent to the Crimean peninsula, which Russia annexed in 2014. Russian forces captured the province’s main city, also called Kherson, on March 3. It was the first major city to fall since Moscow’s military operation in Ukraine began in late February. Vladimir Leontiev, head of the military-civil administration of the Kakhovka region, which is based in Russia, said seven people “definitely” died in the strike. “There are still many people under the rubble. The injured are being taken to hospital, but many people are trapped in their apartments and homes,” Leontiev said in excerpts carried by Russia’s state-run Tass news agency. The development and effectiveness of the Himars system has caused growing concern among pro-Russian figures and military bloggers in Russia. Casualties from the system have mounted as Russian missile defenses in Ukraine appear to be struggling to deal with the launches. Heimaris graphic Alexander Sladkov, a war reporter for state broadcaster Rossiya 1, wrote on Telegram this week that Ukraine was successfully attacking Russian command centers. “Ukrainian missiles and artillery have hit decision-making centers multiple times, with results,” he wrote. “The centers are small but important.” The Moscow Times quoted Russian state television journalist Andrey Rudenko as saying that the attacks in Ukraine’s Khimary were likely behind the explosions at ammunition stores in the cities of Shakhtarsk and Torez. “Heavy fires and explosions. The situation is horrible,” he said. While Ukraine has only a few of the systems, Himars appears to have a disproportionate impact on the number of available launchers. Phillips O’Brien, professor of strategic studies at the University of St Andrews, said the strike at Nova Kakhovka should be “worrying” for Russian forces. “Either way this attack reveals a lot about where we stand,” he tweeted. “The Russians should have known such an attack was a high priority for the Ukrainians, but they either couldn’t or wouldn’t adjust. For them it’s great worrying”. The Institute for the Study of War, a US think tank that monitors the conflict, said Russian forces “continue to focus on defensive operations along the entire southern axis”. Subscribe to First Edition, our free daily newsletter – every day at 7am. BST Serhiy Khlan, a former adviser to the governor of Kherson province, said Russian forces had stepped up security measures, “preparing for civil war in case a Ukrainian counterattack reaches Kherson.” Ukraine has said it expects another attack by Russian ground forces. Meanwhile, the Russian-backed self-proclaimed Donetsk People’s Republic in eastern Ukraine said the results of appeals against death sentences handed down to two Britons and a Moroccan who fought with Ukrainian armed forces would be known within a month. Ukraine and Western countries have said the men are prisoners of war, entitled to protection under the Geneva Conventions.