Several explosions rocked Ukrainian capital Kyiv and the cities of Lviv, Ternopil and Dnipro on Monday.
Ukrainian public broadcaster Suspilne quoted emergency services as saying there were dead and wounded in Kyiv but gave no further details of casualties.
"Several explosions in Shevchenkivskyi district – in the center of the capital," Kyiv Mayor Vitali Klitschko wrote on Telegram, adding that all metro services in Kyiv have been shut down and all stations have been opened as shelters.
The head of the Khmelnytskyi regional military administration, Serhiy Gamalii, reported the sound of explosions in the region, and said the air defense was working.