One of the victims when a cafe was struck during a wake in the Kharkiv region was an eight-year-old boy.
Ihor Klymenko remarked, "There were people here from every home."
The incident was attributed to Russia by the Ukrainian defense ministry, which also said there were no military targets nearby.
On the strike, Russia has not made any specific comments.
In the early hours of Friday, Russia then launched missile attacks on Kharkiv itself, according to mayor Ihor Terekhov.
Speaking to Ukrainian TV, he said that a residential structure was attacked, killing a 10-year-old youngster. Over 20 other people suffered injuries.
Russia probably employed Iskander ballistic missiles in the most recent attack, the mayor continued.
When the missile struck on Thursday, residents of the Hroza village were present at the funeral of a local soldier from the Ukrainian army.
The man's wife, son, and daughter-in-law were all killed, according to local prosecutor Dmytro Chubenko, who was quoted by the Interfax-Ukraine news agency.
The soldier had been interred in Dnipro before, but his family decided to reinter him in his hometown.
When the missile struck the cafe in the village that also acted as a grocery store, people who had attended the service were seated for a meal, according to officials.
According to preliminary evidence, an Iskander missile may have struck the structure, according to Mr. Klymenko.
During an interview with BBC Radio 4's World Tonight, Ukrainian security specialist and journalist Maria Avdeeva suggested that the Russian military may have been informed about the wake.
We can assume that someone disseminated information regarding the location and time of this grouping of people, she said.
According to what we can currently see on Russian propaganda networks, there were no military personnel present for the funeral, which is misleading and untrue because this was mostly a civil function.
Oleh Syniehubov, the regional governor of Kharkiv, called the assault one of the "bloodiest crimes" in the area.
One terrorist strike claimed the lives of "one fifth of this village," he stated.
The deed "couldn't even be considered a beastly act - because it would be an insult to beasts," according to Ukrainian President Volodymyr Zelensky.
Additionally, the incident has drawn criticism on a global scale.
The attack "demonstrated the depths of depravity Russian soldiers are ready to sink to," according to UK Prime Minister Rishi Sunak. His remarks followed a meeting he had with Mr. Zelensky on Thursday at the European Political Community conference in Spain, an international body that was set up last year in part as a response to the invasion of Ukraine.
Karine Jean-Pierre, the press secretary for the White House, called the strike "horrifying" and said it showed why it was crucial that the Ukrainian people continue to receive international assistance.
The incident occurs at a time when the US House of Representatives is becoming more opposed to continuing to assist Ukraine.
Since Russian President Vladimir Putin began his full-scale invasion of Ukraine in February of last year, the Kupyansk district has been the scene of fierce fighting between the Russian and Ukrainian soldiers.
At the beginning of the war, it served as a significant supply depot for Russian forces, but after months of battle, Kyiv took it back in September 2022.