The attack took place at around 6:30 AM in Pul-e-Charkhil area when a suicide bomber hit a minibus, the Ministry of Interior confirmed.
Interior Ministry spokesman Sediq Sediqqi said 14 Nepalese guards were killed and nine others wounded.
The injured included five Nepalese security contractors and four Afghan citizens who were shifted to the hospital.
He said the suicide bomber had waited near the compound housing the security contractors and struck as the vehicle moved through early morning traffic. As well as the bus passengers, several people in an adjacent market were also wounded.
The armed Taliban have claimed responsibility for the blast. Zabiullah Mujahid Taliban spokesman wrote on his Twitter page.