A shell exploded in Russia's Rostov region on Saturday, one kilometer from the border of Russia with Ukraine, TASS News Agency reported, citing a law enforcement source.

The source clarified there were no casualties or damage.

On the same day, the Ukrainian army said one Ukrainian soldier was killed in clashes with rebels in eastern Ukraine. 

"As a result of a shelling attack, one Ukrainian soldier received a fatal shrapnel wound," the military said. 

According to Reuters, multiple explosions were heard in Donetsk in eastern Ukraine on Saturday.