"Four people, including a police officer who had spotted the bomber, lost their lives in this attack," Kabul police chief Esmatullah Dawlatzai told journalists.
Windows of shops lining the street were shattered and a small crater was made in the road by the force of the explosion.
At least four other civilians are thought to have been injured in the explosion. No foreigners were said to have been among the deceased or injured.
Samiullah Ahmad Rahim, an eyewitness to the attack, told the Associated Press news agency that he heard a loud explosion and then saw a large fireball shortly after the blast.
The attack is the third suicide bombing in Kabul this year after 2006's dramatic escalation of bloodshed and insurgency in the country.
Last week a suicide bomber killed four people including an intelligence official in a busy market place. The attack came one day after a bomber dressed as an army official blew himself up outside a police station, killing four officers.
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