The raid took place overnight and involved a unit from the NATO-led International Security Assistance Force (ISAF), said Interior Ministry spokesman Zemari Bashary.
ISAF declined to comment on the raid and directed inquiries to Afghanistan’s National Directorate of Security, whose head reports directly to President Hamid Karzai. The directorate also declined to comment.
Bashary said two Afghan guards were killed and three wounded in the raid, which he said was not coordinated with Afghan troops. He said the incident was being investigated, but did not provide further details.
The use of “night raids” on private homes by foreign troops hunting insurgents has long angered Afghan officials. Rules governing their use were tightened in 2009.
Under new rules, raids must be cleared by Afghan authorities first and must involve Afghan troops.
A police official in Kabul said the security firm raided was called National Tiger and that it was responsible for providing security and transport for at least three Afghan businesses.
Karzai banned all private security contractors from mid-December, with an exception for those guarding embassies, military installations and diplomatic residences and personnel.
The ban, first announced in August, has since been softened and registered companies are now allowed to run out the terms of existing contracts.
The ban sparked concern in Washington that aid work in Afghanistan would suffer as many profit-oriented development projects rely on private security firms for protection.
The government plans to create an independent public force to start securing international development projects.
Violence is at its worst in Afghanistan since US-backed Afghan troops ousted the Taleban in 2001, with record deaths on all sides.
