Mineral-rich Balochistan has been plagued for decades by a separatist insurgency and gunmen have previously targeted laborers seen as outsiders in the region.
"Two gunmen riding on motorbikes opened fire on a group of construction workers in Peshukan Ganz neighborhood of Gwadar," local administration official Munir Zamari told AFP.
"One worker sustained injuries and he is being treated at a local hospital," he added.
The incident was confirmed by another administration official Naeem Bazai, who said that all the workers were from Sindh province.
Nobody immediately claimed responsibility for the attack.
Balochistan is the largest of Pakistan's four provinces, but its roughly seven million inhabitants have long complained they do not receive a fair share of its gas and mineral wealth.
A greater push towards peace and development by Pakistani authorities has reduced the violence considerably in recent years.
The push includes starting work on a massive Chinese infrastructure project -- the China-Pakistan Economic Corridor -- which gives Beijing a route to the Arabian Sea through Balochistan's deep sea port of Gwadar.