By Svitlana Vlasova and Billy Stockwell, CNN

Kyiv (CNN) — Russia launched one of its largest aerial attacks this month on Ukraine overnight, killing at least three people and injuring at least 17 others, according to President Volodymyr Zelensky, as Ukraine’s leader received his first face-to-face briefing with his negotiating team on their arrival back from talks in the US.

“Russia has been carrying out a massive attack on Ukraine,” Zelensky posted on X, adding that more than 650 drones and over 30 missiles were used in the strike. Some 13 regions, about half the country, came under attack, he said.

In the western region of Zhytomyr, a 4-year-old child was killed after a Russian drone struck a residential building, Zelensky said.

Meanwhile, emergency power cuts were imposed across the country with some regions left almost completely without power due to the attack, according to Ukraine’s energy ministry.

The latest bombardment comes after a fresh round of talks to end the war wrapped over the weekend in Miami, where Ukrainian and Russian officials met separately with a US delegation led by White House envoy Steve Witkoff and Jared Kushner, the son-in-law of President Donald Trump.

On the ground, Kyiv’s troops retreated from the town of Siversk in eastern Ukraine on Tuesday, according to the country’s armed forces, as Russian forces pushed through “active offensive operations.”

Ukrainian solders withdrew from the area in Donetsk to “save the lives of our soldiers and maintain the combat capability of our units,” the General Staff of the Ukrainian Armed Forces said in a statement.

“The invaders were able to advance thanks to their significant numerical superiority and constant pressure” despite “difficult weather conditions,” Ukraine’s Armed Forces added.

Moscow broke through swathes of the city this week after a lightning offensive along eastern frontlines over the summer. Even so, Ukrainian troops have maintained “fire control” of Siversk and Russian units are “being blocked,” the country’s armed forces said Tuesday.

“All measures are being taken to reduce the offensive potential of enemy units,” the statement said.

‘Very close to a real outcome’

Ukraine’s delegation arrived back in Kyiv overnight and delivered what Zelensky called a “detailed report” of the talks.

“Not everything is perfect so far, but this plan is in place,” Ukraine’s leader wrote on X overnight, referring to the 20-point document, which forms the core of an agreement framework between Ukraine and the US.

In addition to the core plan, which include security guarantees “between us, the Europeans, and the United States,” Zelensky wrote, there is an additional document detailing bilateral security guarantees between Ukraine and the US. On this latter point, he said, “we are very close to a real outcome.”

Along with security guarantees, previous rounds of talks have also highlighted the centrality of territory in negotiations, and Zelensky made no comment in statements overnight on any readiness to discuss possible land swaps.

Last week, Russian President Vladimir Putin gave a clear indication that he will not compromise on his demands for Ukraine to cede territory in the Donbas, despite the Trump administration’s intensifying push for peace.

In an apparent attempt to tamp down expectations, Kremlin spokesman Dmitry Peskov told the Russian newspaper Izvestia on Monday that talks between Russian and US officials over the weekend should not be considered as a breakthrough.

“This is a working process. We already said that first there needs to be quite a meticulous work process at the expert level,” Peskov said.

Witkoff, who led the US delegation at the Miami talks, said Russia “remains fully committed to achieving peace in Ukraine” after meeting with Kirill Dmitriev, the head of the Russian sovereign wealth fund (RDIF) and a Kremlin special envoy, at the weekend.

He made a similarly worded statement after talks with the Ukrainian delegation. “Ukraine remains fully committed to achieving a just and sustainable peace,” Witkoff said, while noting that their meeting was “constructive” and included discussions about the “sequencing of next steps.”

Away from the Florida talks, Zelensky put Ukraine’s military on alert for potential Russian attacks around Christmas while pointing out the lack of air defenses available to defend the country.

The Ukrainian leader said the most recent attack “sends an extremely clear signal about Russia’s priorities.”

It was an attack “ahead of Christmas, when people simply want to be with their families, at home, and safe,” he said. “An attack carried out essentially in the midst of negotiations aimed at ending this war.”

CNN’s Hira Humayun, Nina Subkhanberdina, Tim Lister and Sana Noor Haq contributed reporting.