A cordon surrounding a section of Queen Street following a suspected gas leak has been reduced.
South Wales Fire and Rescue Service were called to the city centre at 12.30pm after reports of a potential underground fault in a main utility line supplying the street.
Local shops were evacuated and the area was cordoned off to prevent public access into the area.
Wales and West Utilities say engineers discovered a fire on an electrical cable in the basement of a shop.
Fire officers remain at the scene as a precaution.
Fire officers and gas engineers were called to reports of a gas leak at WH Smith in Queen Street today.
Cardiff's fire station commander Justin Jones said the combination of high gas readings and an electrical fault in the shop's basement caused a "perfect storm" and had to be dealt with immediately.
Parts of Queen Street were immediately evacuated including nearby shops.
The fire service says the cordon will remain in place for another few hours.
Emergency services are currently responding to reports of a gas leak in WH Smith in Cardiff City Centre. A large section of Queen Street has been cordoned off with shops evacuated.
It's reportedly causing "major confusion" among shoppers and office workers this lunchtime, with people told to avoid the area.
Commuters have experienced disruption to rail services this morning following a landslide between Cardiff Central station and Queen Street Station.
Workers are desperately trying to fix the problem as tens of thousands of people are expected to descend on the Welsh capital this afternoon for the Olympic football Bronze medal match.