The first known US citizen to die while fighting against Russian forces was a former Marine named William Joseph Cancel, his family told multiple media outlets.

Clean-up crews work at the site of an explosion in Kyiv, Ukraine.

A clean-up crew works at the site of an explosion. Photo/Emilio Morenatti.

ASSOCIATED PRESS

Cancel was working for a private military contracting company when he was killed, his mother told CNN.

He wanted to help contain the conflict in hopes that other U.S. troops wouldn't have to.

The U.K.'s Foreign Office told multiple news outlets that a British national had died and another was missing in Ukraine.

The citizen who died, identified by multiple news outlets as Scott Sibley, was also fighting in Ukraine, according to anonymous diplomatic sources.

The Ukrainian embassy in Copenhagen confirmed to the media on Friday that a Danish citizen had been killed in Ukraine.

The 25-year-old man was fighting in a unit for foreigners who want to fight against Russia.

The reports from Cancel's family members have not been confirmed by the U.S. The State Department said in a statement to Forbes that it was aware of the reports, but had no further comment due to privacy concerns.

Big Number

20,000. Ukrainian Foreign Minister Dmytro Kuleba said that 52 countries have traveled to fight Russian forces. The U.S. and other countries have warned citizens against going to Ukraine to join the fight, despite the creation of the International Legion by Ukrainian President Volodymyr Zelensky.

Tangent

Radio Free Europe/Radio Liberty said that one of their journalists died after Russian shelling hit a residential building. The body of a man was found in the rubble of a building that was hit by a Russian missile. Several journalists have died while reporting on the invasion, including a Fox News cameraman and a Ukrainian journalist.

The American was killed fighting with Ukrainian forces.

Scott Sibley, a British man, was killed in the conflict in Ukraine.