Ukraine announced it has secured the release of 144 Ukrainian soldiers Wednesday in the biggest prisoner swap since the start of Russia’s invasion in February. 

Out of the 144 soldiers released, 95 were individuals who defended the Azovstal steel plant in Mariupol, according to Ukraine’s military intelligence agency. 

The steel plant was under siege at the start of the war, with hundreds of Ukrainian soldiers surrendering in late May.

The surrender came after weeks of negotiating as Russian forces took control of the whole city. 

The intelligence agency said most of the released soldiers have serious injuries from attacks by Russian forces.

“Most released Ukrainians have serious injuries: fire and fragment wounds, explosive injuries, burns, fractures, limbs amputations. They all receive proper emergency medical and psychological help,” the agency said. 

Other released soldiers include 59 from the Ukrainian National Guard, 30 from the Navy, 28 from the Armed Forces of Ukraine, 17 from the State Border Service of Ukraine, nine Territorial Defense soldiers and one from the National Police of Ukraine.

This is one of multiple prisoner swaps that have occurred between Ukraine and Russia during the war. 

The United Nations have accused both Russia and Ukraine of mistreating prisoners of war since February.

Russia has also been accused of multiple war crime violations, with evidence they are targeting civilians, raping women and kidnapping Ukrainians.