STORY: A unilateral ceasefire in Ukraine, declared by Russian President Vladimir Putin, was officially due to come into force on Friday.
But the hours leading up to the temporary truce saw renewed fighting.
Kramatorsk’s mayor said Russian shells hit the city close to the frontline.
While Russia said Ukraine shelled its military positions in the Luhansk, Donetsk and Zaporizhzhia regions - despite its troops observing the ceasefire.
Reuters could not immediately establish if there had been a lull in hostilities after the deadline.
The 36-hour ceasefire, which coincides with Russian orthodox Christmas in the region, was rejected by Kyiv as a trick, adding it had no intention of stopping fighting.
Ukraine and Western allies have said the call is a ploy, aimed at giving Moscow time to reinforce troops and equipment along the eastern front.
Shortly after the ceasefire was due to come into effect, Russian-backed officials accused Ukraine of shelling the city of Donetsk with artillery, according to Russia's state-run TASS news agency.
Despite air raid warnings sounding in several regions, no major air strikes were reported by Ukrainian officials after the starting time.
Putin called the ceasefire in a surprise move on Thursday.
It is the first major truce since Russia invaded on February 24 last year.
The war has killed killed tens of thousands, displaced millions, and devastated swathes of Ukraine.
With financial support and weapons from the United States and Europe, Ukraine has driven Russia back from some of its territory.
But battles are raging over eastern and southern cities.
Among the most intense battlegrounds is the city of Bakhmut, still in Ukrainian hands despite dug-in trench warfare and months of battering by Russian forces that have left much of it in ruins.
On Friday (January 6), Germany announced that it wants to send 40 Marder fighting vehicles by the end of the first quarter to reinforce the country's defences.