The explosion, the latest in a series of bomb blasts to hit Kabul in recent days, came with the city under tight security ahead of this week’s Eid-ul Fitr holiday ending the Muslim holy month of Ramadan.
Interior Ministry spokesman Nasrat Rahimi said the bus was carrying employees of the Independent Administrative Reform and Civil Service Commission when the bomb exploded, enveloping the bus in flames and thick black smoke, Reuters reported.
No group has claimed responsibility for the attack.
The Daesh terror group said it was behind a similar attack in Kabul on Sunday.