Dane “Bird” Partridge, 34, of Idaho, arrived in Ukraine from the United States on April 27.

The American veteran signed on as a legionnaire for Ukraine’s International Legion of foreign fighters, and was wounded on October 3 in Ukraine’s Donbas region. Partridge was in a coma until he passed away while still on life support on October 11.

The father-of-five had “a strong spiritual conviction that he could not deny and wanted to go fight for a noble cause,” his sister, Jenny Corry, told Newsweek.

“He didn’t even have a plan. He bought a one-way ticket to Poland, took whatever equipment he could carry with him on the airplane, and figured he’d make the rest of his plan from there once he got to Poland,” she said.

On October 3, Dane and his team were “ambushed” by two Russian fighting vehicles, in the Donbas region, and he was critically injured, Corry said.

The eastern Donbas region has been one of the flashpoints of the Ukraine war which the Russian President launched on February 24.

“Lacking stretchers, and still under assault by the enemy, his comrades carried him out on a blanket, then rushed him and the other wounded soldiers to hospital in a vehicle, which in the grim attempt to save the men was damaged to the point of having one wheel remaining,” Corry explained.

He died as a result of his injuries at Zaporizhzhia Regional Medical Center on October 11, she said.

Corry said several pieces of shrapnel lodged in her brother’s brain, and that he also had a break in his neck and a wound in his arm.

The State Department confirmed to Newsweek that a U.S. citizen had been killed in the Donbas region of Ukraine.

“We can confirm the recent death of a U.S. citizen in the Donbas region of Ukraine. We are in touch with the family and are providing all appropriate assistance,” a spokesperson said.

More than half-a-dozen Americans have died fighting on the Ukrainian frontlines. In August, Newsweek reported that another U.S. citizen had been killed, while U.S. citizens Luke Lucyszyn and Bryan Young died in July alongside two Canadian and Swedish nationals while volunteering to fight in Ukraine against Russian forces.

Two other Americans that were killed in Ukraine include Stephen Zabielski, a 52-year-old from New York state, and Willy Cancel, a 22-year-old former U.S. Marine from Tennessee.

Cancel was the first American to be confirmed dead in Ukraine, dying on April 25, his family told CNN.

Several Americans have also been captured by Russian forces.

Two U.S. veterans who were serving in a regular Ukrainian military unit, Alexander Drueke, 39, and Andy Huynh, 27, were caught by the Russian military outside Kharkiv in June. They were released in September in a prisoner exchange brokered by Saudi Arabia, a family member told Reuters.

More than 20,000 foreign fighters have joined the war to fight for Ukraine, from more than 52 countries. Many of these – which include veterans from the U.S. Army, U.S. Marine Corps and the British Army – have a lot of prior military experience.

Some Westerners are even training soldiers to fight in Ukraine.

Corry told Newsweek that her family is now working on repatriating her brother’s body to the U.S. so that he can be laid to rest in a veteran cemetery in Idaho.