Three persons were injured in the attack in Mansehra district of Khyber-Pakhtunkhwa province. The injured were taken to a nearby hospital.
Soon after the incident, security forces cordoned off the area and started a search operation.
No group has claimed responsibility for the incident.
Earlier today, At least 18 people, including two women and six children were injured, when a bomb went off in a residential area in Karachi.
Pakistan has witnessed a sharp surge in violence ahead of the May 11 general election. About 100 people have died in bombings and attacks by the Taliban and other militant groups in recent days.