On board Ukraine's frontline hospital bus

STORY: This Ukrainian bus painted with sunflowers is in fact a high-tech medical evacuation unit.

Medics monitor wounded soldiers and keep them stable as they're transported from a small frontline hospital to a larger one in the central city of Dnipro.

The bus belongs to Ukraine's Hospitallers Medical Battalion, which evacuates troops across Ukraine.

Polina is a paramedic who gave no second name.

"We usually transport patients who have gone through surgery in some smaller hospitals. We transport them to larger facilities so the smaller hospitals have fewer patients. Also, the patients we transport will receive treatment from staff who specialize in their injuries."

Rotating teams of volunteers spend several weeks on call.

They're part of a huge network of evacuation teams in Ukraine that links soldiers in trenches to teams in rear positions, then to field hospitals or small local hospitals and in more serious cases, on to larger centers.

The bus was named "Avstriika", after the military call sign of an Austrian volunteer who worked on a similar one before she was killed in a crash.

It replaces the bus that was damaged and building it took six months.

Andrii, a doctor who gave no surname, says it's "the start of a big story".

"We're planning to buy new buses, we're planning to manage that this works, and to create a system, a system that will help our military medical service. And I think our cooperation will become deeper and stronger."

Since Russia invaded Ukraine last February, tens of thousands of soldiers have been killed and wounded on both sides of the conflict.