The so-called Islamic State group later claimed responsibility for the attack.
Moazzam Ali Jatoi, an official with the Levies Force, which serves as police and paramilitary in the area, said the attack took place near the Machh coal field, about 30 miles east of the provincial capital Quetta.
Mr Jatoi said armed men took the coal miners to nearby mountains, where they opened fire.
He said six of the miners died at the scene and five died on the way to hospital.
He said an initial investigation found the attackers identified the miners as being from a Shiite Hazara community and the gunmen took them away for execution, leaving others unharmed.