United Nations staff at UN Headquarters in New York participating in a march to commemorate the International Day of Reflection on the Genocide in Rwanda ten years ago. (UN Photo #UNE7353 by Shraddha Howard)

United Nations staff in New York marching around the circle in front of the Secretariat Building today. (UN Photo #UNE7354 by Shraddha Howard)

United Nations staff in New York marching around the circle in front of the Secretariat Building today. (UN Photo #UNE7355 by Sophie Paris)

United Nations staff in New York marching around the circle in front of the Secretariat Building today. (UN Photo #UNE7356 by Sophie Paris)

United Nations staff in New York marching around the circle in front of the Secretariat Building today. (UN Photo #UNE7357 by Sophie Paris)

The United Nations flag flying at half-mast. (UN Photo #UNE7365 by Eskinder Debebe)

The United Nations flag flying at half-mast, as staff marched in front of the Secretariat Building. (UN Photo #UNE7362 by Eskinder Debebe)

Catherine Bertini, Under-Secretary-General for Management, rings the Peace Bell. (UN Photo #UNE7358 by Sophie Paris)

Catherine Bertini (right), Under-Secretary-General for Management, and Shashi Tharoor (left), Under-Secretary-General for Communications and Public Information. (UN Photo #UNE7358 by Sophie Paris)

A wide view of the UN staff members observing a moment of silence by the Peace Bell. (UN Photo #UNE7368 by Eskinder Debebe)