Ivan Fyodorov, as his name suggests, is an ethnic Russian in a southern Ukrainian city where Russian is commonly spoken and where cultural and familial ties to the motherland run deep.

That would seem to make Mr. Fyodorov, the mayor of Melitopol, just the kind of person to welcome conquering Russian soldiers with open arms and flowers.

Instead, he labeled them “occupiers.”

On Friday evening, those Russian soldiers threw a bag over Mr. Fyodorov’s head and dragged him from his government office, Ukrainian officials said. Security camera footage from Melitopol’s Victory Square appears to show someone being escorted out of a government building by soldiers, but The Times could not verify the identity of the people in the video.