Russian ground forces invade Ukraine after Putin announcement
Ukraine border guards said the death toll so far stood at three.
Russian tanks and other heavy equipment crossed the frontier in several northern regions, as well as from the Kremlin-annexed peninsula of Crimea in the south, the agency said.
It said one of its servicemen died in a shelling attack along the Crimean border, the first officially confirmed military death of the Russian invasion.
Ukraine has suffered heavy casualties in its eight-year conflict with Russian-backed rebels in the separatist east, but has reported no fatalities along its southern border with Crimea for some years.
Emmergency law had come into effect in Ukraine at midnight, while reserves had been called up on Wednesday and Ukrainians told they have to right to carry arms.
Ukraine President Volodymyr Zelensky said his country was ready to resist the Russian invasion.
"No panic. We're strong. We're ready for anything. We'll defeat everyone, because we are Ukraine," he said in a video statement according to the BBC.
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