How an RSF commander's defection led to a massacre in Sudan

At least 80 people were killed in the al-Seriha massacre in Gezira state in Sudan in October .

Eyewitness tells BBC that he saw unarmed civilians gunned down by fighters at close range.

The massacre appears to have been prompted by the defection of a senior RSF commander.

An RSF spokesman denies its fighters were involved in the killings.

BBC has obtained four separate videos of aftermath of the attack on al-Seriha .

Footage shows bodies lined up in the courtyard of a mosque, covered with shrouds and blankets.

The UN has said that 124 people died the reprisal killings in al-Sehira and other towns in Gezira state since Keikal 's defection on 20 October .

The activities of the RSF and the Sudanese military in Gezira state have attracted international condemnation, with the UN and human rights groups expressing outrage. In a statement, the US Ambassador to the UN Linda Thomas-Greenfield urged countries to cease providing arms to both sides of the war. She said supplies were prolonging the conflict. "The people of Sudan have endured hell," she said. "They deserve safety, dignity, and justice. They deserve to live." Additional reporting by Mohanad Hashim . Graphics by Mesut Ersoz ..