The Ukrainian military and Russia-backed separatists have accused each other of violating a cease-fire established ahead of the start of the new school year.
The new truce came into effect on August 25 just after midnight, a week before most pupils in Ukraine return to school on September 1.
The Ukrainian Defense Ministry said that the first breach was recorded less than two minutes into the cease-fire, when the separatists targeted the village of Talakivka in the Donetsk region with small arms and heavy machine guns.
It added that Ukraine’s armed forces “did not give in to provocations and did not open fire in response."
Meanwhile, the separatists in Donetsk said they suffered the first casualty after the truce was established when one of their fighters was killed by the bullet of a Ukrainian sniper.
Several cease-fire deals announced as part of the February 2015 Minsk agreement meant to put an end the conflict in eastern Ukraine have failed to hold.
The latest cease-fire was agreed on August 22 during a phone call between the leaders of Germany, France, Russia, and Ukraine.
Fighting between Kyiv's forces and the Russia-backed separatists in the eastern Ukrainian regions of Donetsk and Luhansk has killed more than 10,000 people since April 2014.