Mortar rounds struck an apartment building overnight near Donetsk, in eastern Ukraine, the latest violation of a cease-fire agreement between Ukraine and pro-Russia separatists that went into effect earlier this month. Ukraine’s military said eight soldiers were also wounded in overnight fighting.

Although both sides agreed to a cease-fire Sept. 5, back-and-forth shelling has been taking place on an almost daily basis. Another agreement was signed Saturday calling on Ukraine and the separatists to pull back heavy artillery. The parties said they were seeing progress on that accord

"The situation remains difficult," Col. Andriy Lysenko, spokesman for Ukraine's National Security and Defense Council, told the Associated Press. Lysenko called the pro-Russia separatists “terrorists.”

"Ukrainian detachments comply with the cease-fire regime but the terrorists continue provocations," he said.

At least two apartments in the heavily damaged residential building were destroyed by the mortar rounds, AP reported. The Russia-based RIA Novosti news agency quoted rebels who said two civilians were killed, but nobody near the building could confirm that account.