Kabul provincial police chief Mohammad Ayuob Salangi said the powerful car bomb blew up at about 4:30 a.m., leaving a deep crater at the first gate leading into the camp.
"Four Nepali guards, one Afghan guard and two Afghan civilians have been killed," Kabul police chief Mohammad Ayoub Salangi said.
Salangi said that the attack started with a suicide bomb carried in a large truck, then two or three insurgents engaged guards with gunfire for 30-40 minutes.
The blast left a large crater in the ground and all the assailants were killed, he said.
There was no immediate claim of responsibility, but Taliban insurgents have said they were behind most of the recent strikes in Kabul, which come as pressure grows on the Afghan government to seek a peace deal with the rebels.
(with agency inputs)