Ukrainian President Volodymyr Zelensky said up to 1,000 people were in the mall when it was hit by missiles, adding: “The number of victims is impossible to imagine.”
Later on Monday, the head of the Poltava region military administration, Dmytro Lunin, said 10 people had died and 40 were injured in the attack.
“We don’t know how many more people might be under the rubble,” said Volodymyr Solohub, a regional official in the Poltava Oblast local administration.
Video from the scene showed heavy smoke billowing from the building, which was engulfed by fire. The mall measures about one hectare — roughly the size of two football fields — and the strike occurred around 4 p.m. local time, Solohub said.
The attack targeted a site in central Ukraine far away from the epicenter of Russia’s war, which has recently been focused in the east of the country.
Russia has been gaining ground in eastern Ukraine in recent days, capturing the city of Severodonetsk after weeks of fighting and picking up territory south of Lysychansk.
It has eliminated most Ukrainian defenses in the Luhansk region and consolidated control of a belt of territory in the south, bringing strategic benefits and blunting the effectiveness of Ukrainian counterattacks.
Russian forces have also stepped up attacks in the Donetsk region, getting slightly closer to the belt of industrial towns in the region that runs south from Sloviansk through Kramatorsk to Kostiantynivka.
The G7 vowed to continue providing support for Ukraine “for as long as it takes” in a joint statement at their summit on Monday.
The US plans to announce as early as this week that it has bought an advanced, medium-to-long-range surface-to-air missile defense system for Ukraine, a source familiar with the announcement told CNN.
“Zelensky was very much focused on trying to ensure that Ukraine is in as advantageous a position on the battlefield as possible in the next months as opposed to the next years, because he believes that a grinding conflict is not in the interest of the Ukrainian people,” US national security adviser Jake Sullivan said after the Ukrainian President met virtually with leaders.
Earlier, a source familiar with the matter told CNN that Zelensky told leaders he wanted the war to be over by the end of the year, before winter sets in.
CNN’s Tim Lister contributed reporting.