An international aid organization says five of its staffers have been taken for questioning in northern Syria.

An official with Doctors Without Borders says the five staffers have been out of contact since Thursday evening.

Media Relations Manager Michael Goldfarb did not say if the five had been taken by government forces or rebels fighting to overthrow President Bashar Assad, and refused to give further details in order to protect their safety.

He said Friday the five were taken from a Doctors Without Borders house in northern Syria "allegedly for questioning."

Goldfarb refused to reveal their nationalities.

Kidnappings of journalists, aid workers and activists are not uncommon in rebel-held areas in Syria.