Denis Mikhail

The coal miners worked for DTEK, Ukraine's largest private energy company.

DTEK spokesman Pavlo Bilodad told NPR that this is the deadliest attack on the company's workers since Russia's full-scale invasion began nearly four years ago.

Writing on social media, Ukraine's energy minister, Denis Mikhail, called it, quote, a cynical and targeted attack on energy workers.

In another part of south-central Ukraine, at least six people were injured after a Russian attack on a maternity hospital in the city of Zaporizhia.

Meanwhile, Trump administration envoy Steve Witkoff said this weekend that talks with Russia have been, quote, productive.

Joanna Kekisis, NPR News, Kyiv.