Russia launched its deadliest attack on Kyiv in months overnight Wednesday, firing waves of ballistic missiles and drones that killed at least 27 people and wounded scores more, prompting Ukrainian President Volodymyr Zelenskyy to vow "definite" retaliation.

The massive combined strike included approximately 74 missiles and 476 drones launched across Ukraine, according to Ukrainian military sources. The barrage set apartment buildings ablaze and sent over 50,000 civilians fleeing to subway stations for shelter as air raid warnings sounded across the capital.

Day of Mourning Declared

Kyiv Mayor Vitali Klitschko declared July 3 a Day of Mourning for victims of the attack. National flags on municipal buildings will fly at half-staff, with authorities recommending that both public and private institutions do the same.

In the Darnytskyi district, a Russian strike destroyed part of a high-rise residential building. Rescuers spent Thursday searching for a 15-year-old girl and her family trapped beneath the rubble, exemplifying the human toll of the overnight assault.

Zelenskyy Visits Attack Sites

President Zelenskyy toured damaged apartment buildings and vowed retaliation for what he described as deliberate attacks on civilian infrastructure. "Ukraine will definitely retaliate for Russia's attack on Kyiv," Zelenskyy declared during his visit to the destroyed residential block.

The Ukrainian leader also renewed calls for Western allies to provide additional air defense systems, specifically requesting a license for Ukraine to manufacture Patriot missiles domestically. The EU's top diplomat announced plans to propose new sanctions against Russia in response to the strikes.

Russia Claims Retaliation

Russia said the strikes were in retaliation for recent Ukrainian drone attacks on Russian energy infrastructure. The assault came after weeks of Ukrainian strikes deep inside Russia that have put pressure on President Vladimir Putin and sparked domestic criticism of Russia's air defenses.

Military analysts noted the strike represented a significant escalation, with the combination of missiles and drones suggesting Russia sought to overwhelm Ukraine's air defense systems.

Deadliest Spring Since 2022

The attack caps the deadliest spring for Ukrainian civilians since the opening months of Russia's full-scale invasion in 2022. Both sides have raced to develop new weapons and tactics, with violence increasing as the war enters its fourth year.

Beyond Kyiv, the Russian strikes also impacted the Sumy, Dnipro, Zaporizhzhia, Cherkasy, and Kharkiv regions. NATO allies are preparing for next week's summit in Ankara, where Ukraine's defense needs are expected to dominate discussions.

A recent study found that Russia's invasion has caused more than 2 million military casualties on both sides, underscoring the devastating human cost of Europe's largest ground war since World War II.