Following reports of a gas odour in the building, fire crews were dispatched to the Trafalgar Road site around 5.30pm. on Wednesday evening.
When firefighters arrived on the scene, they discovered an ammonia leak. The building was evacuated and a hazmat team was called in.
Residents living nearby have also been told to stay off their balconies while emergency services make the area safe.
Crews will be on the scene for the next few hours to ventilate the building to safe levels.
Following that, the building was returned to maintenance crews.