Islamabad, Oct 11 (IANS): Twenty labourers were killed and six others injured in attacks on multiple coal mines in Pakistan's Balochistan province in the wee hours of Friday morning, officials said.

The incidents happened in the Duki district of the province, where unidentified attackers targeted at least ten coal mines with hand grenades, killing and injuring the labourers working inside, the district's political head Haji Khairullah Nasir told media.

He said the attackers set the mines and extraction machinery on fire before fleeing the scene. The district's police told the media that some of the miners were grouped and shot dead by the attackers, Xinhua news agency reported.

The bodies and injured labourers were shifted to a nearby hospital, where several of the injured were in critical condition, police said.

Most of the victims were residents of different districts of Balochistan, police said.

No group claimed responsibility for the attack.