Five staff members of the medical charity Medecins Sans Frontieres were kidnapped overnight in Cameroon's Far North, a region where militant group Boko Haram operates, the aid group said on Friday.
The workers were organising humanitarian projects in the area when armed men broke into MSF's residence in the town of Fotokol, an MSF representative told Reuters.
"Teams are mobilised to support our five colleagues," they said.
Neither the identity of the attackers nor their motives were immediately known, MSF said.
The incident occurred in an area where a rise in inter-communal clashes has displaced nearly 100,000 people and in December killed dozens. Attacks by Boko Haram militants are also common.
(Reporting by Josiane Kouagheu and Cooper Inveen; Editing by Edward McAllister and Alison Williams)