Malnourished and dehydrated people are crawling through the desert on their elbows and knees in constant terror of being caught by fighters from Sudan’s paramilitary Rapid Support Forces (RSF), humanitarian organizations have warned.

The journey from the RSF-controlled city of el-Fasher to the town of Tawila is just 30 miles, but nonetheless perilous as gunmen rove around, robbing people, taking them hostage and in some cases slaughtering them by the dozen, the organizations say…