An American humanitarian worker who had served in the US military was killed while assisting civilians in Bakhmut, Ukraine, an aid organisation and his family confirmed on Friday.
Pete Reed, the founder of Global Response Medicine, died on Thursday, the aid group said on Twitter.
“Pete was the bedrock of GRM, serving as board president for four years,” his organisation said.
“In January, Pete stepped away from GRM to work with Global Outreach Doctors on their Ukraine mission and was killed while rendering aid.”
The US State Department confirmed that an American had died, but did not share the victim's identity.
“We can confirm the recent death of a US citizen in Ukraine. We are in touch with the family and providing all possible consular assistance,” a State Department representative told The National.
Fox News first reported news of Mr Reed's death.
The former US Marine Corps rifleman served in two tours in Afghanistan before starting humanitarian work in his home country and abroad, his organisation said.
Mr Reed worked in Haiti, Poland, Syria and Yemen.
He also worked with medics in the Kurdish Peshmerga and Iraqi special forces against ISIS militants during the battle for Mosul.
Family members, including his brother and cousin, posted about Mr Reed's death on Facebook.
“Fly on home, lovely man, soul and caretaker of so many in their last days, no doubt. You will be so missed by so many,” his cousin Randy Repass Jr wrote.
Mr Reed's passing makes the sixth known death of an American citizen in Russia's war on Ukraine, after volunteers from around the world travelled to help fend off Moscow's invasion that is nearing its one-year mark.