“A search and rescue operation is underway in Dnipro at the site of a four-story apartment building. Part of the building was effectively demolished,” Zelenskyy said Tuesday, adding that Russia fired more than 650 drones and 70 ballistic, cruise and anti-ship missiles at Ukrainian communities overnight.

“A large-scale attack and a completely transparent statement from Russia: if Ukraine is not protected from ballistic and other missile strikes, these strikes will continue,” he said. “Assistance from the United States in supplying missiles for Patriot systems is absolutely necessary,” he added.

Later in his early evening address, Zelenskyy said intelligence services had warned a “massive attack” could come Tuesday night too.

At least six people were killed and 65 injured, including three children, across Kyiv, Mayor Vitali Klitschko said, as multiple multistory residential buildings in the capital either caught fire or were damaged in attacks.

More than 41,000 people flooded into the Kyiv subway system seeking shelter early Tuesday — the highest number of people recorded in the metro during a nighttime air raid alert in recent years, the metro said on social media.

Among them was Olena Kozachenko, 36, who told NBC News that before Russia intensified its attacks in recent months, she and her 8-year-old son “almost never went to shelters.”

“Now it feels like we’re seeing a new level of attacks against civilians,” Kozachenko said in a telephone interview Tuesday, adding that “after seeing many warnings in the evening that the night could be dangerous, we planned in advance to spend it in the metro.”

“Once missiles are already incoming, there’s no point trying to get farther than the apartment,” she said.

Ukraine has warned for weeks about dwindling supplies of air defense missiles to protect its cities, worried they were being used up in the war in the Middle East.

“If we don’t have sufficient air defenses, then these large-scale attacks will slowly erase our city,” Kozachenko said.

With U.S. diplomacy stalled amid that shift in focus, Russia has targeted Ukraine’s power supply and infrastructure while Ukraine has stepped up attacks on Russian oil facilities.

The Russian Defense Ministry acknowledged the attack Tuesday, saying it was targeting military infrastructure in response to what it called “the terrorist attacks by the Kyiv regime.” Moscow maintains it doesn’t target civilians despite years of attacks that have leveled entire Ukrainian towns and left thousands of civilians dead or injured.

Russia warned last week that it intended “systematic strikes” on targets in Kyiv linked to the Ukrainian military, as well as decision-making centers, and urged foreigners to leave.

It said the action was in response to a drone strike last month on a dormitory in Ukraine’s Russian-held region of Luhansk, which killed 21. Russia has called it a terrorist attack against children, though Ukraine denied targeting civilians.

At a meeting with officials dedicated to that attack Monday, Russian President Vladimir Putin appeared to issue another warning. He said that Kyiv had given the war a “new dimension” by striking the dormitory. “That is their choice,” he added.

The Ukraine war has ground on since Russia launched its full-scale invasion in February 2022. Efforts to end it have made little progress, with President Donald Trump focused on the Middle East.

Anastasiia Parafeniuk reported from Kyiv and Yuliya Talmazan and Elmira Aliieva from London.