Russian airstrikes targeting energy and other facilities rocked Ukraine from east to west Tuesday, causing broad power blackouts. A senior official warned that the situation was “critical” and urged Ukrainians to “hang in there” as neighborhoods went dark.

The aerial assault, which resulted in at least one death in a residential building in the capital, Kyiv, followed days of euphoria in Ukraine sparked by one of its biggest military successes in the nearly nine-month war — the retaking last week of the southern city of Kherson.

At least a dozen regions reported strikes, which caused multiple emergency blackouts.

A Ukrainian air force spokesman said Russia fired around 100 missiles. President Volodymyr Zelenskyy put the number at 85.

Zelenskyy warned that more attacks may be coming but defiantly vowed, with a shake of his fist: “We will survive everything.”

A senior official, Kyrylo Tymoshenko, said the barrage was “another planned attack on energy infrastructure facilities.”

“Most of the hits were recorded in the center and in the north of the country. In the capital, the situation is very difficult,” Tymoshenko wrote on Telegram.

It was difficult elsewhere, too.

As its battlefield losses mount, Russia has in recent months increasingly resorted to targeting Ukraine’s power grid, seemingly hoping to turn the approach of winter into a weapon by leaving people in the cold and dark.

While city after city reported attacks, Tymoshenko appealed to Ukrainians to hang on and acknowledged the severity of the situation.

Among regions where officials reported strikes were Lviv, Zhytomyr, Khmelnytskyi and Rivne in the west, and Kharkiv, Ukraine’s second largest city in the northeast. Several missile strikes also hit Kryvyi Rih, Zelenskyy’s native city, according to its mayor, Oleksandr Vilkul.

In Kyiv, Mayor Vitali Klitschko said authorities found a body in one of three residential buildings that were struck in the capital, where emergency blackouts were also announced by power provider DTEK.

Video published by a presidential aide showed a five-story, apparently residential building in Kyiv on fire, with flames licking through apartments. Klitschko said air defense units also shot down some missiles.

Ukraine had seen a period of comparative calm since previous waves of drone and missile attacks several weeks ago.

The strikes came as authorities were already working furiously to get Kherson back on its feet and beginning to investigate alleged Russian abuses there and its surrounds.

The southern city is without power and water, and the head of the U.N. human rights office’s monitoring mission in Ukraine, Matilda Bogner, on Tuesday decried a “dire humanitarian situation” there.

Speaking from Kyiv, Bogner said her teams are looking to travel to Kherson to try to verify allegations of nearly 80 cases of enforced disappearances and arbitrary detention it has turned up in the area and “understand whether the scale is in fact larger than what we have documented already.”

The head of the National Police of Ukraine, Igor Klymenko, said authorities are to start investigating reports from Kherson residents that Russian forces set up at least three alleged torture sites in now-liberated parts of the wider Kherson region and that “our people may have been detained and tortured there.”

“Mine clearance is currently underway. After that, I think, today, investigative actions will begin,” he said on Ukrainian TV.

The retaking of Kherson was one of Ukraine’s biggest successes in the nearly 9-month-old Russian invasion and dealt another stinging blow to the Kremlin. But large parts of eastern and southern Ukraine remain under Russian control and fighting continues.

Zelenskyy on Tuesday likened the recapture of the Kherson to the Allied landings in France on D-Day in World War II, saying both were watersheds on the road to eventual victory.

“It’s like, for example, D-Day — the landing of the Allies in Normandy. It was not yet a final point in the fight against evil, but it already determined the entire further course of events. This is exactly what we are feeling now,” he said in a video address to a Group of 20 summit in Indonesia.

The liberation of Kherson — the only provincial capital that Moscow had seized — had sparked days of celebration in Ukraine and allowed families to be reunited for the first time in months. But as winter approaches, the city’s remaining 80,000 residents are without heat, water or electricity, and short on food and medicine.

Still, U.S. President Joe Biden called it a “significant victory” for Ukraine. Speaking on the sidelines of the G-20 summit, Biden added: “We’re going to continue to provide the capability for the Ukrainian people to defend themselves.”

Zelenskyy warned of possible more grim news ahead.

“Everywhere, when we liberate our land, we see one thing — Russia leaves behind torture chambers and mass burials. … How many mass graves are there in the territory that still remains under the control of Russia?” Zelenskyy asked.