Tymur Tkachenko, head of the local regional military administration, said at least 50 residential buildings had been damaged in the attack, which also sparked a large-scale fire that spread to homes and a restaurant.
In a statement, Ukrainian President Volodymyr Zelenskiy said a warehouse had been struck in the village of Myla "followed by a detonation."
He did not give details on the site, but wrote in the same message that criminal proceedings had been opened on charges of official negligence.
"There are regulations in place - ammunition cannot be stored near homes or other residential areas," Zelenskiy said.
The Ukrainian leader wrote that a care home for elderly people and people with disabilities and residential buildings were damaged.
"More than 370 people have already been evacuated, and the evacuation is ongoing," he said.
Almost constant air raids in Kyiv have reached their third day, choking the economy in the Ukrainian capital and severely disrupting civilian life more than four-and-a-half years after Russia's full-scale invasion of its neighbour.
Earlier, Ukraine's top presidential adviser said technical talks on Russia's war will likely take place in the near future.
"I think everyone will see the negotiations happening very soon. But this will mainly concern the technical side of things and preparations for something big, which I hope we will eventually get to," Kyrylo Budanov said in an interview for YouTube project Moseichuk+.
US-backed peace talks have so far led to no tangible results to end the war.
The last round of trilateral negotiations took place in February.
Asked if fighting would drag on through the winter, Budanov said it was "unrealistic" to expect the war to end now.
In recent months, both sides have significantly stepped up attacks on logistics, port infrastructure and energy facilities.
Russia is also expected to renew its relentless campaign against Ukraine's power grid as winter approaches.
Ukraine and Russia need to reach a point where they are ready to simultaneously take a step toward each other, said Budanov, who is his country's representative at the talks, adding that Ukraine was open to this.
"And as of now, the Russian Federation - and I'm telling you this as someone who is deeply involved in this process - is saying outright, 'we might want to but no'."
Kremlin foreign policy aide Yuri Ushakov declined to comment on reports a new round of talks with Ukraine could take place in September with US participation.
Ushakov said he had seen media reports about the proposal but could not say anything concrete.
Russia's key demand is Ukraine's withdrawal from the eastern Donbas area, which Russian troops have not managed to fully occupy during their more than four-year full-scale invasion.
Ukraine says it will not cede territory it still controls.
The International Atomic Energy Agency said it has been informed of three drone incidents at the Russian-held Zaporizhzhia nuclear power plant in southeastern Ukraine earlier this week.
The United Nations nuclear watchdog said a drone attack on August 25 reportedly occurred near the plant's cooling pond, injuring two plant employees, while two other drones on August 26 reportedly struck the site's dry spent nuclear fuel storage area and the sprinkling device of the power units system.
Radiation levels at the Zaporizhzhia plant remained normal, the watchdog added.
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