Russia bombarded the Ukrainian capital with a furious missile and drone attack before dawn on Thursday, killing at least six civilians in an assault that came soon after President Trump had warned Moscow of new sanctions if such violence persisted.

Rescuers raced to more than two dozen locations around the capital, Kyiv, to put out fires and search for survivors in the rubble of blasted apartment buildings.

“We have 52 injured, nearly 30 hospitalized,” Tymur Tkachenko, the head of the city’s military administration, said in a statement at 7 a.m. local time. “Among them, nine children were injured.” One child was among the deceased.

The number of dead and wounded was likely to grow, Mr. Tkachenko warned.

The assault came shortly after President Trump threatened new sanctions on Moscow if President Vladimir V. Putin did not put a halt to the bloodshed in 10 days. Russian officials dismissed the warning, and many in Kyiv saw the bombardment as Mr. Putin’s way of thumbing his nose at the United States.

The bombardment began around midnight with swarms of drones packed with explosives descending on the city from multiple directions.

Tracer fire from heavy machine guns lit up the sky as air defense crews struggled to keep up with the barrage. Drones exploded over city streets as residents raced to find shelter wherever they could.

At 3:20 a.m., the Air Force issued an all-clear signal, but the threat quickly resumed at approximately 4:30 a.m.

This time, the threat came from ballistic missiles. The sky lit up as they slammed into the city center, with one striking a nine-story apartment building.

At least 27 locations around Kyiv were hit in either direct strikes or by falling debris, mainly in the city’s Solomianskyi district, the authorities said.

President Volodymyr Zelensky shared video footage of one residential building reduced to ruins. “People are under the rubble,” he wrote. “All services are on site. Russian terrorists.”