Update: Fire and Rescue NSW Inspector Jeremy Hood, Duty Commander Illawarra, said the electrical business at the southern end of the complex suffered the majority of fire damage.
He said heat and smoke damage was caused to the adjoining business Play Maze, while no apparent damage had been caused to the Master Builders Association at the northern end of the complex.
Earlier: Smoke is affecting visibility on the Princes Highway at Unanderra after a building fire earlier on Thursday.
The blaze, which started in an electrical shop in an industrial complex near First Avenue, has been extinguished.
The fire was contained to the electrical shop, but smoke can be seen coming from adjoining businesses including Playmaze.
Firefighters are inside the building, with a HAZMAT truck and ladder truck on scene for support, a spokesman for Fire and Rescue NSW said.
Emergency services were alerted to the fire after 19 phone calls to 000 from the public about 7am.
Endeavour Energy have cut power to the industrial complex.
Drivers near the incident are urged to exercise caution.
MORE TO COME