An explosion occurred when a school bus carrying nearly 100 children passed by on Quetta's Hana Road on Tuesday, security sources said.
Miscreants targeted the bus, which was coming from Sorenje area of the city, through a roadside bomb, Levies sources said.
All children remained safe in the incident, however, the driver of the bus suffered light injuries.
Levies sources said the bus was carrying children of employees of Pakistan Mineral Development Corporation (PMDC).
They said the glasses of the bus windows were smashed due to impact of the blast. Levies, police and Frontier Corps personnel reached the site as an investigation into the incident went underway.
Balochistan has faced a number of security challenges in recent months, with security personnel in the province often being targeted in roadside explosions and suicide attacks.
Fifteen people, including eight soldiers, were martyred when a suicide bomber targeted a military truck near the Pishin bus stop in Quetta last month.
Earlier in June, 14 people ─ including seven policemen ─ lost their lives in a suicide blast that shook Shuhada Chowk in Quetta's Gulistan Road area.
Balochistan has been experiencing incidents of violence and targeted killings for over a decade. More than 1,400 incidents targeting the minority Shia and Hazara community have taken place in the province during the past 15 years.