Six men launched an attack on the National Directorate of Security (NDS) facility in Kabul's Sedarat area at midday, detonating a car bomb at the gate before attempting to storm the facility.
All six men have been killed, officials said.
One man was driving the car when it exploded at the NDS main entrance and five more men were shot in a subsequent gunfight with security guards as they attempted to force their way through the gate, according to Ministry of Interior spokesman Sediq Sediqi and Kabul police chief Gen. Ayub Salangi.
A second car rigged with explosives has been found in the same street and the bomb has been disabled, Sediqi told TOLOnews.
As many as 20 other people have been either killed or injured but exact numbers have not been confirmed, according to the chief of Kabul police criminial investigation unit Gen. Zahir Zahir.
The wounded have been taken to the nearby NDS hospital and emergency wards of other local hospitals, officials said.
The bomb blast blew the glass out of windows of a row of shop fronts on the opposite side of the road, burned trees, and damaged cars in the street.
The targeted NDS facility includes the site of the only NDS prison in Kabul.
NDS head Asadullah Khalid survived an assassination attempt last month carried out by a suicide bomber who entered the NDS facility in Kabul's Taimani area in a planned meeting with the intelligence chief.
To watch a video clip of aftermath of the attack, click here:
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