According to Ferdaws Paramarz, Kabul police spokesman, the incident happened at about 8am in PD7 in Chehelsetoon area.
A magnetic IED was detonated against the vehicle which is believed to have been a government car.
However the identities of the victims have not yet been released.
This latest incident comes amid a spate of targeted attacks and killings against civilians in the capital in recent months.
Not only are government employees being targeted but assassinations of public figures including civil society activists and media workers have also been on the rise.