The target was a police post near the military headquarters, a ministry spokesman said.
A police officer at the scene told Reuters the attack appeared to have been carried out by a suicide bomber on foot.
A Reuters witness reported seeing several damaged cars, with possible injuries to the occupants.
There was no immediate claim of responsibility, but terrorists belonging to various groups including the Taliban and ISIS have claimed recent attacks in Kabul.
Last month, ISIS killed nearly 50 people when then stormed the main military hospital in Kabul.
(Reporting by Mirwais Harooni, Editing by Nick Macfie)
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