Twelve-year-old Abdiwahab - not his real name - sobs as he recounts what happened to him as he escaped from the western Sudanese city of el-Fasher.

The young boy left el-Fasher on Sunday as it fell to the paramilitary Rapid Support Forces (RSF), the group fighting a two-and-a-half-year civil war against the army.

In a video received by the BBC, his face reflects deep sorrow and fatigue, his voice low as he describes being assaulted many times by RSF fighters.

Fearing reprisal from RSF fighters, Abdiwahab joined a wave of people, including some family members, trying to get out.

The UN estimates that 60,000 have successfully escaped from el-Fasher, many narrating horrific stories of atrocities, including rape.

After three days traversing perilous terrain, Abdiwahab reached the relative safety of Tawila, an 80km (50-mile) journey, but he arrived alone.

''I left the city with my father and siblings, but because of the chaos we were separated, I came to Tawila alone, he says.

He faced threats on the journey, accused of espionage. I walked along the road, and on the road, [the RSF] caught me, many times. They beat me and hit me, saying, 'this little boy is a spy'. This reflects a dire reality where men and boys are especially at risk of arbitrary arrest and violence.

Abdiwahab's mother and one sister were taken about a month earlier by RSF forces; he does not know if they are still alive.

A fellow escapee, Ali, now a volunteer aid worker, filmed Abdiwahab’s harrowing account as he arrived at a makeshift camp in Tawila.

Ali described how the boy, traumatized by his experiences, kept asking for his parents. I decided to take him home until we found them, he said.

Arrivals at the camp bring tales of survival amid chaos; many arrive with serious health conditions and injuries, and aid organizations are overwhelmed.

Women have endured attacks from armed men during their escape, now relying entirely on humanitarian assistance.

The UN's refugee agency continues to struggle to provide shelter and food for the influx of civilians, as reports of mass killings in el-Fasher emerge, with the RSF admitting to violations in the city.

Estimates suggest over 260,000 civilians remain trapped in el-Fasher, facing dire conditions.