A cigarette thrown onto some bin bags sparked a fire outside a property in Bridport town centre.
Firefighters were alerted to the scene behind a shop in the early hours of Sunday after bin bags caught alight.
Crews said a serious fire was averted after a resident arrived home and raised the alarm after smelling smoke.
Firefighters warn that cigarettes should be disposed of in an appropriate manner.
A spokesman for Bridport Fire Station said: "On arrival at the scene crews were shown the first floor balcony at the rear of a shop where rubbish bags had been left and had caught fire.
"A resident had attempted to extinguish the fire from their second floor window.
"Crews used a hose reel jet to fully extinguish the fire.
"The accidental fire was believed to have been caused by a discarded cigarette landing in the bin bags. "Luckily the resident had returned home and after smelling smoke and hearing the smoke alarm found the fire. This prevented what could have been quite a serious fire.
"Ensure cigarettes are fully extinguished and disposed of in an appropriate manner."
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