A U.S. soldier guards Afghanistan's interior ministry in downtown Kabul.

Two Americans - believed to be a U.S. colonel and major - were shot dead inside the building on Saturday.

NATO's International Security Assistance Force (ISAF) spokesman - Brigadier General Carsten Jacobsen.

(SOUNDBITE) (English) ISAF SPOKESMAN, BRIGADIER GENERAL CARSTEN JACOBSON, SAYING:

"What we can confirm so far is that in the inner city of Kabul an individual pulled his weapon and opened fire on members of the International Security Assistance Force. We can confirm that two ISAF personnel were killed in this incident."

The shootings occurred as rage over the burning of Korans at a NATO base continues to grip the country.

Afghanistan's Taliban movement has claimed responsibility for the shootings, saying they were in retaliation for the desecration of the Muslim holy book.

Katharine Jackson, Reuters.