(CNN)  Three aid workers have been kidnapped in Darfur; two are Sudanese, and one is an American citizen.  The American is a 36-year-old woman from California.  The aid workers were working for a North Carolina-based international relief organization called Samaritan’s Purse.  They were traveling in a two-vehicle convoy on Tuesday about 25 miles outside of Nyala when they were kidnapped by armed men.  Spokeswoman Judith Razen confirmed that the US Embassy is working toward their release, and Samaritan’s Purse is likewise working with US and Sudanese government officials so that the workers can be freed.