One of the evacuated residents said she first smelt gas about 2pm today.
"I certainly thought you could smell it at 2 o'clock. I didn't think anything of it," she said.
Emergency services staff had shown up at the door of her flat and "told us to get out".
A block of 16 flats had all been evacuated.
Among those evacuated was Vi McCormick.
"One of the men came around and told me I had to leave," she said.
She had time to grab her dog, Shay, and leave.
A police officer at the scene said the source of the leak was yet to be identified.
A contractor alerted emergency services after smelling gas while working on the road, he said.
Nova Gas was on site to help firefighters locate the source of the gas and a St John ambulance was also there as a precaution.
About 100m stretch of the road had been closed to the public.
Firefighters wearing breathing apparatus could been seen using water to suppress the gas.
A block of 16 flats and neighbouring houses had been evacuated.