The U.S. Embassy in Kyiv said on Wednesday Russian forces had shot and killed 10 people waiting in line for bread in the Ukrainian city of Chernihiv.
The embassy did not cite what evidence it had of the attack in a statement posted on its official Twitter site and on its Facebook page.
Russia has called its military actions in Ukraine a "special operation". It did not immediately comment on the U.S. embassy statement. Moscow denies targeting civilians in Ukraine.
"Today, Russian forces shot and killed 10 people standing in line for bread in Chernihiv. Such horrific attacks must stop. We are considering all available options to ensure accountability for any atrocity crimes in Ukraine," the embassy said.
(Reporting by Natalia Zinets, Writing by Alessandra Prentice, Editing by Timothy Heritage and Toby Chopra)