Two aid workers with Doctors Without Borders have been freed , the group says . At the time of their kidnapping , Serrat , of Girona , was 40 , and Thiebaut , of Madrid , was 30 , the group said . They were kidnapped in December 2011 . The kidnapping came during an attack at one of the world 's largest refugee camps .
Two aid workers with Doctors Without Borders have been freed , the group says . They were kidnapped in December 2011 . The kidnapping came during an attack at one of the world 's largest refugee camps .