Russia launched one of its deadliest overnight attacks in months across Ukraine, killing at least 12 people — including three children — and injuring dozens, Ukrainian officials said Sunday.

The drone and missile strikes, which hit Kyiv, Zhytomyr and Mykolaiv, came as Kyiv and Moscow completed the largest prisoner exchange since the war began, swapping more than 1,000 soldiers and civilians over the weekend.

In Zhytomyr, west of the capital, three children aged 8, 12 and 17 were killed when drones hit residential areas, Ukraine’s state emergency service reported. Four more people died in the Kyiv region, where multiple homes were set ablaze; and a 70-year-old man was killed in Mykolaiv after a drone struck a five-story apartment block, according to a BBC report.

Nearly 300 attack drones and almost 70 missiles — including ballistic missiles — were fired overnight, Ukrainian President Volodymyr Zelenskyy said on X.

The Russian airstrikes came despite a diplomatic breakthrough, as the two sides on Friday started the biggest POW exchange since Russian President Vladimir Putin launched his full-scale invasion in 2022.

U.S. President Donald Trump praised the prisoner swap, posting on Truth Social: “Congratulations to both sides on this negotiation. This could lead to something big???” — even though the exchange had not yet started when Trump posted his message.

“[Trump] wanted to be the first to break the news about it,” a Ukrainian official told POLITICO on condition of anonymity. Ukraine’s Defense Minister Rustem Umerov thanked Trump for his involvement, as Kyiv is still trying to keep the U.S. president engaged in efforts to broker peace in Ukraine.

Meanwhile, Trump and Putin held a two-hour call last week to discuss a U.S.-proposed 30-day ceasefire. Trump called the talks “very successful,” but Putin has so far only agreed to explore a nonbinding “memorandum” outlining potential peace terms.

Zelenskyy on Sunday condemned the overnight strikes and urged international allies to step up pressure on Moscow to end the conflict.

“Russia is dragging out this war and continues to kill every day,” the Ukrainian president said in a post on X. “The world may go on a weekend break, but the war continues, regardless of weekends and weekdays. “This cannot be ignored. Silence of America, silence of others around the world only encourage Putin,” he added.

“Determination matters now — the determination of the United States, of European countries, and of all those around the world who seek peace,” Zelenskyy said. “Without truly strong pressure on the Russian leadership, this brutality cannot be stopped.”

Veronika Melkozerova contributed to this report.