Black plumes of smoke could be seen across the city Thursday evening after a fire broke out on the rooftop of an apartment complex in the River-Osborne area. 

The blaze broke out just before 7 p.m. in an 18-storey apartment building at 221 Stradbrook Avenue, near Donald Street. 

Heavy black smoke and flames were seen billowing from the rooftop when crews arrived at the scene. Firefighters made their way to the roof, using the building's standpipe system to battle the fire. The fire was declared under control a short time later. 

Most residents self-evacuated before firefighters arrived. Others had to be evacuated by firefighters. One person was transported to hospital in unstable condition. A firefighter was also transported to hospital in stable condition. No other injuries were reported. 

While fire damage was mostly isolated to the roof, the building sustained extensive water damage, and residents were unable to return to their suites. 

The cause of the fire is under investigation.