Two Americans who were killed alongside a pair of Canadian and Swedish nationals while volunteering to defend Ukraine from Russia’s invasion earlier this month have now been identified.

Luke Lucyszyn and Bryan Young were the US citizens killed during an ambush by a Russian tank on 18 July, their Ukrainian commander said on Facebook. The attack in which they died also killed Emile-Antoine Roy-Sirois of Canada and Edvard Selander Patrignani, according to the commander, Ruslan Miroshnichenko.

Citing an account from Miroshnichenko, Russian shelling left Lucysyzyn wounded, and that prompted Young and the others to try to help him, CBS News reported. Additional tank fire killed the four foreign volunteers in the Donetsk region, a heavily disputed region of Ukraine, Miroshnichenko said.

Miroshnichenko’s remarks came after the US state department late last week announced the recent deaths of two Americans in Ukraine, without releasing any additional details. They are among at least six Americans who have died in Ukraine since it was invaded by Russia in February.

Lucyszyn’s parents, Kathryn and George, told NBC News that their son had gone to Ukraine in early April to volunteer as a medic. He worried that his group lacked necessary equipment and asked his folks to send over a tactical vest and other supplies, the couple from Calabash, North Carolina, said.

“He didn’t go there to be a hero,” Kathryn Lucyszyn said of her 31-year-old son. “He went there because he wanted to help people.”

Miroshnichenko said his unit nicknamed Lucyszyn “Skywalker” after the protagonist of the original Star Wars film trilogy who shared his first name.

Likening their struggle to that of Luke Skywalker, Miroshnichenko called Lucyszyn, Young, Roy-Sirois and Patrignani “warriors of light and good, heroes of Ukraine”.

US officials, including the president, Joe Biden, have discouraged Americans from volunteering to defend Ukraine. While the government is helping the Ukrainian defense by providing billions of dollars in weapons and other resources, it says it is limited in its ability to help American citizens once things go awry there.

Many US nationals have nonetheless still travelled to the country during the conflict.

Americans who have been killed there include video journalist Brent Renaud; Jimmy Hill, who was gunned down while waiting in a bread line; Stephen Zabielski, who was slain during fighting in May; and Willy Joseph Cancel, who died during battle in April.

Meanwhile, at least two other Americans were taken prisoner by Russian forces during a gunfight in June: Alexander Drueke and Andy Tai Ngoc Huynh, both of Alabama.

A statement from Drueke’s family late Sunday said the US state department has spoken with him at least four times, though it appeared each of the calls was scripted, and therefore it was difficult “for them to assess the men’s treatment and conditions.”

The Kremlin has threatened both prisoners with possible execution though their families are hopeful the US and Ukrainian governments can negotiate their release.