The blast occurred on Thursday afternoon in Malang Jaan road in Jalalabad City.
Eyewitnesses say that all of the victims are civilians who were using public transportation services.
Provincial governor spokesman Ataullah Khogyani told Ariana News that explosives were placed inside the bus and five people were injured in the incident.
But a health official in the province said that at least 10 injured people including three children were taken to the hospitals for treatment.
Immediately there was no claim of responsibility for the attack.