Hundreds of Sudanese villagers were killed when a landslide engulfed their village in Darfur, a region already stricken by famine and war, according to officials and a local rebel group that issued an urgent appeal on Tuesday for international help.

The landslide happened on Sunday after days of heavy rain and leveled the village of Tarsin in the remote Marra mountains, the Sudan Liberation Movement/Army said in a statement.

The rebel group said that as many as 1,000 people had been killed in the disaster, with just a single survivor in the village. The toll was based on estimates of the village population.

The top U.N. official in Sudan, Luca Renda, said in a statement that between 300 and 1,000 people may have died. Sudan’s government and aid workers scrambling to reach the affected area offered similar estimates.

“This is a nightmare,” Abdul Wahid al-Nur, the leader of the rebel group, said by phone from Nairobi on Tuesday. He asked the United Nations and aid groups to send heavy machinery and rescue workers, saying, “We need to move thousands of tonnes of rock and earth.”

“Our biggest problem is that nobody is coming to help. This is beyond our capability,” he added.

The landslide was the latest calamity to befall a region already ravaged by Sudan’s two-year civil war and the world’s largest humanitarian crisis.