QUETTA: Four labourers involved in road construction were killed by unknown gunmen in the Yakmach area of Kharan district on Thursday.According to Levies sources, all the victims were residents of Sindh and were constructing a road in the Yakmach area when some armed assailants riding motorbikes came there and opened fire at them and fled from the spot.As a result, they died on the spot after receiving bullet wounds. The bodies were rushed to a nearby hospital where the victims were identified as Ghulam Mustafa, Sajad, Niazi and Surab Khan.Local administration cordoned off the entire area and started efforts to arrest the suspects.