Marty Hine, general manager of Millwright Engineering on Ashley Place, said businesses in the area were stopped from accessing the road while the police activity was underway at a nearby property.
He said staff arrived about 7am but were stopped from entering the area.
Other workers who were already inside the workshop were told to remain in the building, he said.
Hine said he did not know what police were responding to but said at around 10am, businesses were now being allowed back onto the road.