Tensions were high in the anti-terrorist operation zone in southeastern Ukraine over the past day as clashes went on in three operative sectors, the army operation press center said.

"ATO forces were shelled by BM-21 Grad rocket launchers, artillery, mortars, guided missile launchers, self-propelled howitzers and light weapons 115 times. Most bombardments and clashes occurred during the day, and the last shots were fired in Mariupol area near the town of Chermalyk at 1415. Last night was relatively calm in the ATO area," the press center wrote on Facebook on Friday morning.

According to the press center, militants conducted 21 attacks on army positions from 1800 till 0600.

Grad rocket launchers shelled Krymske, Tonenke and Debaltseve, while there were four mortar, artillery and self-propelled howitzer attacks on Stanytsia Luhanska and two attacks on Yunokommunarivsk. Krymske, Pryshyb, Petrivka, Triokhizbenka, Opytne, Maryinka, Zolote, Semyhirya, Kamenka, Mykolaivka and Shakhta Poltavska were shelled too, the press center said.

According to the Ukrainian army, the militia shelled populated localities in Luhansk region eight times.

In turn, self-proclaimed Donetsk People's Republic (DPR) defense ministry political department chief Eduard Basurin said that three civilians were killed and another six injured in the Ukrainian bombardments last night.

"In all, 16 civilians were killed and 18 were injured over the past day," he said.