Two Nato officers have been killed inside the Ministry of Interior in the Afghan capital Kabul, coalition officials say.
The International Security Assistance Force (Isaf) said in a statement that two of its members had been shot dead.
They were an American colonel and major, Afghan security officials say. Local media reports suggest the incident followed a "verbal clash".
The ministry has been put under lock-down, officials say.
"An individual turned his weapon against International Security Assistance Force service members in Kabul City today", the Isaf statement said.
Early reports suggest the two were shot in the ministry's command and control centre.