A photograph taken by 22-year-old US soldier Hilda Clayton of the moment an explosion killed her and four other soldiers has been released by the US Army.

Specialist Clayton and four Afghan National Army (ANA) soldiers died when a mortar tube accidentally exploded during a training exercise under the supervision of US Army trainers in July 2013.

Specialist Clayton was 22 when she was killed while photographing the training exercise. ( Supplied: US Army )

Almost four years later, the Army University Press, a US Army multimedia organisation, has released two images of the accident — one taken by Specialist Clayton and another taken by an ANA soldier.

US military newspaper Stars and Stripes reported that Specialist Clayton's family and unit approved of the release of the photos, according to an official from the Army University Press.

One of the Afghan soldiers killed was a photojournalist Specialist Clayton had partnered with to train in combat photography, but it is not clear whether they were responsible for taking the second image.

An article published in the Army University Press's Military Review said the accident occurred during a "critical juncture of the war, when it was necessary for the ANA to increasingly assume responsibility for military actions".

It said Specialist Clayton helped document the "strengthening" partnership between ANA soldiers and the US during that time.

The article said her death symbolised "how female soldiers are increasingly exposed to hazardous situations in training and in combat on par with their male counterparts".

Defending their decision to publish the photographs, Military Review said the edition focused on gender equality and the dangers their "military men and women faced both in training and in combat".

Specialist Clayton was the first "combat documentation and production specialist" to be killed in Afghanistan.