Sudan’s paramilitary Rapid Support Forces (RSF) killed hundreds of civilians, including hospital patients, after seizing el-Fasher, the last army stronghold in Darfur, according to the U.N. and aid workers.

Witnesses described mass executions, sexual violence, and attacks on hospitals as residents fled the city.

Satellite imagery and reports from humanitarian groups confirmed large-scale killings and targeted assaults on medical facilities, which the U.N. said amount to war crimes, ABC News has reported.

Global outrage followed, with Western governments condemning the atrocities and U.S. lawmakers calling for the RSF to be designated a terrorist organization.