Ukraine secured the release of more than 100 women held as prisoners of war in a swap with Russia on Monday.

Kyiv released 110 Russians in return for 108 Ukrainian women in what Ukrainian presidential chief of staff Andriy Yermak called Ukraine’s “first all-female exchange” of the war.

The overwhelming majority of the women released Monday are fighters in Ukraine’s armed forces. Twelve of the women released are civilians.

“Mothers and daughters were in captivity, and their relatives were waiting for them,” Yermak said.

The Russian Ministry of Defense confirmed the swap, and said two Ukrainian prisoners had “voluntarily refused to return to Ukraine,” opting to stay in Russia.

The ministry said those Russian citizens released included 72 Russian sailors from civilian vessels who’d been detained by Ukraine at the start of the war.

Ukrainian President Volodymyr Zelensky said Monday that 37 women involved in the defense of Azovstal were among those released.

A sprawling, Soviet-era steelworks, Azovstal served as site of Ukrainian defenders’ last stand in the ruined port city of Mariupol this spring. The women and their comrades holed up in the complex for weeks, enduring near-constant shelling while repulsing several Russian attempts to storm the plant.

Zelensky said that some of the prisoners had been captured by Russian forces before the full-scale invasion, ostensibly during the on-again off-again skirmishes in the Donbass that played out following Russia’s 2014 incursion.

“Among those released today are those who were captured long before the full-scale war,” he said. “We do not forget about any of our people – we have to return them all. And we will return them all.”

Zelensky also thanked Ukrainian forces for “replenish[ing] our exchange fund” by capturing Russian soldiers.

“The more Russian prisoners we have, the sooner we will be able to free our heroes. Every Ukrainian warrior, every frontline commander should remember this,” he said.