An Afghan guard at a United Nations compound in Kabul turned his gun on colleagues on May 20, killing a Nepalese guard and wounding another security officer there.
The United Nations Assistance Mission for Afghanistan said one of its staff members at the compound also was wounded by the shootings.
Hassib Sediqi, a spokesman for Afghanistan's National Directorate of Security, said the violence happened at a construction site that is part of the UN compound.
It was not immediately clear if the attack was planned as an act of terrorism or the result of a disagreement.
The construction site at the UN compound is next to the International Organization for Migration and opposite buildings from the UN assistance mission in Kabul.
The violence came a day after an Afghan police officer killed eight other Afghan police in what was called an "insider attack" in the southern province of Zabul.
The Taliban claimed responsibility for the May 19 attack.
Based on reporting by AP and Reuters