It started as a low drone, the sound of an Antanov bomber flying high above. Its flight crew had spotted a rebel convoy, and the hum of prop engines grew louder as soldiers and journalists scrambled from the vehicles and scurried down the banks of a dry riverbed to hide under overhanging trees.

Watching the white plane circling overhead, they waited and wondered where the bombs would land. Eventually, a dull thud was heard - then two more - as bombs exploded about a kilometer and a half away.

These Soviet-era aircraft are not renowned for their accuracy. The empty fields of southern Blue Nile state are pockmarked with craters and towering, bulbous Baobob trees are scarred by shrapnel.

But the psychological effect of these sorties is almost as destructive as the explosions themselves. People in rebel-controlled areas live in constant fear of the bombers, and a distant hum sends them scurrying for cover.

"We hear the voice of the Antonov and we know it well," said Hawa Jundi. "When I hear the Antonov coming I am really very scared. So I look for my kids and we just run to the river to hide."

Like tens of thousands of people in Blue Nile, Jundi fled her village of Saly after it was bombed. She and her family now live in a temporary shelter constructed from a tarpaulin strapped to a frame made of sticks.

The Sudan Peoples Liberation Movement-North (SPLM-N), which is fighting the government, says as many as 600,000 people have moved to camps like this since the bombing began in early September.

The number of internally displaced people is impossible to verify. Humanitarian organizations pulled out when the bombing began, and human rights groups have had no access to the area.

Desperate days

During the first visit by journalists into Blue Nile since the fighting began - a trip coordinated by rebel organizers based in Juba, South Sudan's capital - reporters saw first hand the desperate living conditions of people who have fled their villages for fear of being bombed.

Before they left their village, Jundi and her family grew crops to feed themselves. Now they manage to eat once a day by collecting wild plants and sorghum from abandoned farms.

But even here she is unable to escape the Antonov. Earlier that day she said she narrowly escaped being hit by a piece of shrapnel when a bomb fell in a river where she and others were searching for bits of gold they could sell to buy food.

"I don't know why the Antonov came and bombed us, but we left our village and came here," she said. "And after we came here, we found that the Antonov is coming also to this place."

Malik Agar, the leader of the SPLM-N, accused the regime of Omar al Bashir of intentionally bombing civilians as part of a campaign of terror.

"The main strategy of Khartoum to bomb the civil population is to break the will of the combatants," he said. "These are the relatives of the combatants - fathers, mothers, wives, children - so they think this will break the will of the fighters."

The government has denied targeting civilians, saying it is only attacking rebel positions. But human rights groups have accused the regime of intentionally bombing the civilian population in Darfur, as well as in South Kordofan where the SPLM-N is also active.

International appeal

Speaking at his bush camp headquarters, Agar called on the international community to put pressure on the regime to stop bombing civilians and allow humanitarian groups to bring aid to the displaced. He warned that food and medicine are running out in Blue Nile and urgent action is needed to avoid a humanitarian catastrophe.

At the only hospital in rebel-controlled territory, in Kurmuk town, Dr Evan Atar said medical staff treat anyone - civilians, government soldiers captured by the rebels, or SPLM-N fighters. But he said he would soon be out of even basic supplies like gauze and saline solution. During the past month, as fighting raged across southern Blue Nile state, the hospital has gone through a supply that would usually last six months.

In one room, nurses dressed the wound of an SPLM-N soldier who arrived from the front line after being shot in the leg. The man emitted an eerie howl as he lay on the gurney, staring blankly upwards. Atar explained that the soldier had been heavily dosed with Ketamine, a drug that causes hallucinations.

"At the beginning, we give full anesthesia where he sleeps completely," said Atar. "“But now when it comes to dressing we can't continue giving the full anesthesia all the time, so we give something that makes him feel there is no pain."

In another ward, Alton Osman lay partially covered by a jungle-print blanket. His right arm was covered in bandages and he had another large pad of white gauze affixed to his thigh. In a whisper, the frail, old man said he was injured by a bomb dropped near his farm.

Osman was lucky enough to be found by SPLM-N soldiers who brought him to the hospital before he bled to death on the side of the road.

On the run

In the village of Maiyes - a three-hour drive away from Kurmuk and its hospital - churned up earth and household items scattered around a waist-deep crater are all that remains of a hut that until six days ago was home to a family of six. The entire family died when a bomb fell on their home, villagers said.

Residents of Maiyes said they were not ready to completely abandon their village. Instead, they were sleeping hidden among trees along a nearby river and returning to work in their fields at night when the Antonovs don't fly. But they still feared being spotted from above.

"Yesterday there were two Antonovs and they were circling for an hour. We were very scared," said Khidir Abusita, the village chief.

The war may eventually drive these villagers, and displaced people scattered throughout the area, into refugee camps in Ethiopia.

The UN recently reported that 3,500 people had crossed into Ethiopia in one week alone, bringing the total number of refugees there to at least 28,500. As fighting continues, and food and medical supplies run ever lower, that number is sure to rise.

Author: Jared Ferrie, Kurmuk, Sudan
Editor: Rob Mudge