A Ukrainian military spokesman said Russia had continued assaults in several areas on the eastern front and prosecutors said two people had been wounded along with the 55-year-old woman killed by bombs fired at the northern Sumy region.
Reuters could not independently verify the attacks.
No Russian missiles or drones were recorded in Ukraine's airspace on Thursday morning after the Kremlin-sponsored ceasefire kicked in at midnight, the air force said.
The Russian ceasefire falls on the 80th anniversary of the World War II defeat of Nazi Germany, for which Russian President Vladimir Putin is hosting Chinese President Xi Jinping and other leaders for a military parade on Red Square on May 9.
Ukraine, like the West, marks the anniversary on May 8.
President Volodymyr Zelenskiy took a rare walk in central Kyiv to pay his respects to fallen Ukrainian soldiers at a vast mound of Ukrainian flags planted on a grassy verge on the central square.
There was no sign of his security detail in the selfie video he filmed as he passed pedestrians on the city's main drag, at one point pausing to say "hi" as cars tooted their horns and deriding Friday's planned pomp-filled ceremony in Moscow.
"There will be a parade of cynicism. You simply cannot call it anything else. A parade of bile and lies. As if not dozens of allied states, but Putin personally defeated Nazism," he said.
Ukraine has not committed to abide by the ceasefire, calling it a ruse by Putin to create the impression he wants to end the war, which began when Russia launched a full-scale invasion of Ukraine in February 2022.
Putin says he is committed to achieving peace.
Ukraine launched successive drone attacks on Moscow this week, which had forced the closure of airports in the Russian capital and the grounding of airliners.
Reuters witnesses near the front in eastern Ukraine said on Thursday that they heard about eight rounds of outgoing fire and distant sounds of impacts.
In their sector, a small Russian raiding party had tried to advance, but been stopped by Ukrainian drones, they said, but overall, the level of activity was well below normal for that part of the front.
Zelenskiy said on Wednesday that his country stood by its offer to observe a 30-day ceasefire to give diplomacy a chance but that Russia had not responded.
Zelenskiy's top aide said Ukraine had held online talks with US, French, British and German senior officials and discussed ways to pressure Russia into agreeing to a 30-day ceasefire.
In his nightly video address, Zelenskiy appeared to acknowledge the numerous drone attacks that had been targeting Russian sites, including the city of Moscow, as the World War II commemorations approached.
Moscow Mayor Sergei Sobyanin had said before the Russian ceasefire took effect that 14 Ukrainian drones headed for the capital had been repelled or destroyed.
There were no reports from Russia on any Ukrainian attacks on Thursday.
The US proposed the 30-day ceasefire in March and Ukraine agreed, but Russia has said such a measure could be introduced only after mechanisms to enforce and uphold it were put in place.
Both countries are under pressure from US President Donald Trump to bring a swift end to the war, the biggest conflict in Europe since World War II.
