Russia launched a major ballistic missile assault on Kyiv late Saturday, carrying out Moscow’s explicit vow to punish Ukraine for a deadly strike in the occupied east.

The barrage shook the capital’s government district and sent residents fleeing into metro stations as sirens warned of an ongoing threat.

“The capital has come under a mass ballistic missile attack,” Tymur Tkachenko, head of the Kyiv City Military Administration, wrote on Telegram.

“There are currently reports of at least 4 locations affected by the attack: Shevchenkivsky, Dniprovsky and Podilsky districts. Fires and damage to residential buildings are preliminarily reported,” he continued.

“A strike drone attack is ongoing; the ballistic missile threat remains present. Stay in shelters!”

Medical teams were dispatched to the Podilsky district in the northwest of Kyiv, where debris fell in a non-residential area, according to CBS. The attack also caused a fire nearby.

Saturday’s strikes are a retaliatory response to Ukrainian bombardments in Russian-occupied Luhansk, which Russia says destroyed a student dormitory, killing 18 people, according to the Russian emergency ministry.

Ukraine denies responsibility for this and asserts that its military struck only a drone command unit in the area in compliance with international law.

Putin said the Ukrainian military must have known what they were targeting.

The US Embassy and Ukrainian authorities warned the public on Saturday of a possible and substantial attack in the capital after Russia indicated it would issue “inevitable and severe punishment” to those responsible for the dormitory destruction.

Most of those killed in the Luhansk dorm attack were between 23-and 28-years-old.

On Friday, the United Nations said that it “strongly condemns any attacks against civilians and civilian infrastructure, wherever they occur,” and that they could not verify the legal legitimacy of the attack.