An accidental fire believed to be started by a cigarette butt has firefighters cautioning Winnipeggers.

The fire was reported to Winnipeg Fire Paramedic Service (WFPS) just before 10 p.m. Friday.

A storage shed on the third-floor balcony of a three-storey condominium in the first block of Burland Avenue was emitting heavy smoke. Firefighters say flames extended from the structure to the attic.

WFPS declared the fire under control at 10:47 p.m.

Most occupants of the building self-evacuated safely. The remaining individuals were assisted by WFPS crews in evacuating the complex.

There were no injuries reported and residents were able to return to their suites later in the night. No damage estimate is available.

WFPS is reminding residents to use extra care when disposing of cigarette butts.

"Smoking material should always be extinguished in a proper ashtray or deep metal container. Cigarette butts should also never be thrown from balconies, car windows, or disposed of near any vegetation such as grass, leaves or brush," the City of Winnipeg says.

Residents are also reminded to never use a plant pot as an astry, as potting soil is a mix of dirt and several combustible organic materials. A cigarette butt disposed of in this manner can smolder for several hours, warming up the container.

Once heated, the container can crack, providing oxygen to the smouldering material and allowing a flame to spread.