Rescuers searched through charred rubble of a shopping mall Tuesday looking for more victims of a Russian missile strike that killed at least 18 and wounded scores in what Ukraine’s president called “one of the most daring terrorist attacks in European history.” President Volodymyr Zelensky said many of the more than 1,000 afternoon shoppers and workers inside the mall in the city of Kremenchuk managed to escape. Giant plumes of black smoke, dust and orange flames billowed from the wreckage as emergency crews combed through broken metal and concrete for victims. Drones whirred above, clouds of dark smoke still emanating from the ruins several hours after the fire was extinguished. Casualty figures rose as rescuers sifted through the smoldering rubble. The regional governor, Dmytro Lunin, said at least 18 people were killed and 59 others sought medical assistance, of whom 25 were hospitalized. The region declared a day of mourning Tuesday for the victims of the attack. Read:Biden urges Western unity on Ukraine amid war fatigue “We are working to dismantle the construction so that it is possible to get machinery in there since the metal elements are very heavy and big, and disassembling them by hand is impossible,” said Volodymyr Hychkan, an emergency services official. At Ukraine’s request, the U.N. Security Council scheduled an emergency meeting in New York on Tuesday to discuss the attack. In the first Russian government comment on the missile strike, the country’s first deputy permanent representative to the United Nations, Dmitry Polyansky, alleged multiple inconsistencies that he didn’t specify, claiming on Twitter that the incident was a provocation by Ukraine. Russia has repeatedly denied it targets civilian infrastructure, even though Russian attacks have hit other shopping malls, theaters, hospitals, kindergartens and apartment buildings in the four-month war. On Tuesday, Russian forces struck the Black Sea city of Ochakiv in the Mykolaiv region, damaging apartment buildings and killing two, including a 6-year-old child. A further six people, four of them children, were wounded. One of them, a 3-month-old baby, is in a coma, according to local officials. The missile strike on Kremenchuk occurred as Western leaders pledged continued support for Ukraine and the world’s major economies prepared new sanctions against Russia, including a price cap on oil and higher tariffs on goods. Meanwhile, the U.S. appeared ready to respond to Zelenskyy’s call for more air defense systems, and NATO planned to increase the size of its rapid-reaction forces nearly eightfold — to 300,000 troops. Zelenskyy said the mall presented “no threat to the Russian army” and had “no strategic value.” He accused Russia of sabotaging “people’s attempts to live a normal life, which make the occupiers so angry.” In his nightly address, he said it appeared Russian forces had intentionally targeted the shopping center and added, “Today’s Russian strike at a shopping mall in Kremenchuk is one of the most daring terrorist attacks in European history.” He said Russia “has become the largest terrorist organization in the world.” Russia has increasingly used long-range bombers in the war. Ukrainian officials said Russian Tu-22M3 long-range bombers flying over Russia’s western Kursk region fired the missiles, one of which hit the shopping center and another that struck a sports arena in Kremenchuk. The Russian strike echoed earlier attacks that caused large numbers of civilian casualties — such as one in March on a Mariupol theater where many civilians had holed up, killing an estimated 600, and another in April on a train station in eastern Kramatorsk that killed at least 59 people. “Russia continues to take out its impotence on ordinary civilians. It is useless to hope for decency and humanity on its part,” Zelenskyy said. The United Nations called the strike “deplorable,” stressing that civilian infrastructure “should never ever be targeted,” U.N. spokesman Stephane Dujarric said. Group of Seven leaders condemned the attack in a statement late Monday saying “indiscriminate attacks on innocent civilians constitute a war crime. Russian President Putin and those responsible will be held to account.” Read:Russia strikes Kyiv as Western leaders meet in Europe The attack coincided with Russia’s all-out assault on the last Ukrainian stronghold in eastern Ukraine’s Luhansk province, “pouring fire” on the city of Lysychansk from the ground and air, according to the local governor. At least eight people were killed and more than 20 wounded in Lysychansk when Russian rockets hit an area where a crowd gathered to obtain water from a tank, Luhansk Gov. Serhiy Haidai said. The barrage was part of Russian forces’ intensified offensive aimed at wresting the eastern Donbas region from Ukraine. Over the weekend, the Russian military and their local separatist allies forced Ukrainian government troops out of Lysychansk’s neighboring city, Sievierodonetsk. To the west of Lysychansk on Monday, the mayor of the city of Sloviansk — potentially the next major battleground — said Russian forces fired cluster munitions, including one that hit a residential neighborhood. Authorities said the number of victims had yet to be confirmed. The Associated Press saw one fatality: A man’s body lay hunched over a car door frame, his blood pooling onto the ground from chest and head wounds. The blast blew out most windows in the surrounding apartment blocks and the cars parked below, littering the ground with broken glass. “Everything is now destroyed,” said resident Valentina Vitkovska, in tears as she spoke about the blast. “We are the only people left living in this part of the building. There is no power. I can’t even call to tell others what had happened to us.” The Russian forces also pummeled other Ukrainian cities, killing at least five people and wounding 15 others in Kharkiv, Ukraine’s second-largest city and striking the key southern Black Sea port of Odesa where a missile attack destroyed residential buildings and wounded six people, including a child, according to Ukrainian authorities. In Lysychansk, at least five high-rise buildings and the last road bridge were damaged over the past day, Haidai said. A crucial highway linking the city to government-held territory to the south was rendered impassable.