Central Otago More FM announcer Rebecca Flannery said staff at the radio station noticed a strong smell of gas in the building and contacted the fire brigade.
"Everyone noticed it and it was definitely enough to make you feel a bit headachy."
The Currie Motors Toyota building, which houses three other businesses, including the radio station, was evacuated shortly after 1pm.
The Alexandra Fire Brigade officer in charge, Station Officer Shane Ryan, said any report of a gas leak was taken seriously.
A short section of the state highway, near the business, was closed while the matter was investigated, Mr Ryan said yesterday.
"Obviously, we don't want to cause too much disruption, and people have been good about it, but then we treat a hazard such as a gas leak pretty seriously. Because it was lunchtime, many of the people from the building were out anyway."
Gas-detecting equipment was used but failed to pick up any trace of gas at the scene, he said.
"It seems to have already dispersed."
None of the workers in the building required medical attention.
