Sudan’s Rapid Support Forces may have committed genocide as fighters executed thousands of civilians who desperately attempted to flee the West Darfur region last summer. That’s according to Human Rights Watch, which collected the testimonies of over 200 witnesses who described children, still alive, being “piled up and shot” by RSF fighters as part of an ethnic cleansing campaign against the Masalit people and other non-Arab communities. The U.N. estimates some 15,000 people may have been killed in El Geneina last year, while hundreds of thousands were displaced by the violence. A Sudanese woman described to UNICEF how the mother of her 4-year-old niece Yasmine was killed as they fled El Geneina.

Aicha Abakar Abdallah: “Her mother, who was eight months pregnant, was killed, and she, Yasmine, was left all alone. Some people found her on the road and brought her back here. On the road, we suffered a lot. The Rapid Support Forces killed and wounded so many people. … We were living peacefully until the conflict broke out. There was shooting near our home, and we were trapped. When we finally managed to get out, we were beaten and robbed. We came with nothing from Sudan.”

Human Rights Watch is demanding the U.N. and African Union urgently impose an arms embargo on Sudan and deploy security forces to Darfur.