A senior government official in Pakistan says gunmen have attacked a dam construction site in southwestern Baluchistan province, killing at least 20 workers and wounding three.

Commissioner Pasand Khan Buledi of Makran division says a large group of gunmen attacked a labor camp near the dam construction site in the Gobdan area of district Turbat early Saturday. He says the gunmen overpowered eight security guards, shot sleeping laborers and fled.

The commissioner says 16 of the dead were from Pakistan's Punjab province and four were from Sindh province.

No group has claimed responsibility for the attack.

Baluchistan is the scene of a low-intensity insurgency by nationalist and separatist Baluch groups who want substantial share of revenue from gas and mineral resources and complete autonomy from Islamabad.