STAROBILSK, Russian-controlled Ukraine, May 22 — Russian President Vladimir Putin on ​Friday ordered his military to prepare options to retaliate against Ukraine for what he described as a drone attack on a student ‌dorm that killed six people and wounded dozens, with 15 still unaccounted for.

Putin said the attack had struck the dorm in Starobilsk in Luhansk, a Russian-controlled region in eastern Ukraine.

He said Kyiv’s military must have known what it was targeting.

Ukraine’s military denied the Russian accusations and said it had struck an elite drone command unit in the area. It said that ​Kyiv complied with international humanitarian law.

Putin said in his own statement, which was carried by state TV, that there were no military ​targets near the dorm.

“There are no military facilities, intelligence service facilities, or related services in the vicinity. Therefore, there ⁠is absolutely no basis for claiming that the munitions struck the building as a result of our air defense or electronic warfare systems. The ​strike was not accidental; it came in three waves, with 16 drones targeting the same location,” Putin told officials.

The Russian military had been ordered to draw ​up options for Moscow to retaliate, he added.

Reuters was not able to independently verify what happened. Both sides deny deliberately targeting civilians in the war.

Ukraine wants to recapture Luhansk, one of four eastern regions that Moscow unilaterally claimed as its own in 2022 in what Kyiv denounced as an illegal land grab.

Yana Lantratova, Russia’s human rights commissioner, said that 86 ​teenagers aged 14 to 18 had been asleep inside the hostel belonging to Luhansk Pedagogical University’s Starobilsk college when Ukrainian drones had attacked it during ​the night.

Leonid Pasechnik, the top Russian-installed official in Luhansk, said two people had been pulled from the rubble. Maria Lvova-Belova, presidential commissioner for children’s rights, said up to ‌18 children ⁠could still be trapped.

Some children being treated in the hospital were reported to be in a serious condition, Lvova-Belova said.

Lyubov Yakovlevna, a local resident, told Reuters she had heard loud explosions from the attack, which she said had been carried out first by rockets and had targeted what she described as a former base.

She said she had then heard drones which had targeted the student dorm, causing fires to break out and people to seek shelter ​in her apartment block.

“A shock wave ​went through our apartment. Nobody could ⁠sleep all night. We were watching the fires. I was afraid, I was shaking, it was really terrifying,” she said.

Kremlin calls attack ‘monstrous’

Kremlin spokesman Dmitry Peskov called for those responsible to be punished.

“This is a monstrous crime. An attack ​on an educational institution where children and young people are present,” he told reporters.

Moscow said the UN Security ​Council would hold ⁠an emergency session in New York later on Friday to discuss the incident.

Russia’s Foreign Ministry said the Ukrainian strike had pulverized the top three of the hostel’s five floors.

“We call on international organizations, national governments and the global community to give an honest assessment … and to strongly condemn the bloody terrorist attack,” it ⁠said in ​a statement.

Photographs and video released by the Russian authorities showed rescue workers stretchering one man ​out of the rubble, severely damaged buildings — one of which appeared to have partially collapsed — and fires still burning.

President Volodymyr Zelenskiy last week promised retribution after laying red roses at the rubble ​of a Kyiv apartment building where a Russian missile strike had killed 24 people, including three children.