Ukraine on Thursday accused Russia of detaining and killing civilians in the border town of Vovchansk in the northeastern Kharkiv region, where Russian forces launched a ground assault last week.
"Russian troops are taking civilians prisoner," Interior Minister Igor Klymenko said in a post on Telegram.
"According to intelligence reports, the Russian military, trying to gain a foothold in the city, did not allow local residents to evacuate: they began abducting people and driving them to basements."
He said there were also "reports of the first shootings of civilians by the Russian military."
"One of the residents of Vovchansk tried to escape on foot, refused to follow the commands of the invaders, and was killed by the Russians."
Regional police had opened a "war crimes" investigation into the allegations, Klymenko said.
AFP could not verify the claims. There was no immediate response from Moscow to the allegations.
Ukraine has evacuated almost 9,000 people in the week since Russian forces stormed across the border in a surprise ground assault.
Russian soldiers have previously been accused of executing civilians in parts of Ukraine they captured and controlled since they invaded in February 2022.
In April 2022, the bodies of dozens of civilians, some with their hands tied up, were found in the Kyiv suburb of Bucha after a month-long occupation by Russian forces.