Eight fire engines and around 60 firefighters were called to a fire at row of terraced houses on Cowick Road in Tooting.
The first floor and roof of two properties were destroyed by the fire. Most of the ground floor of both properties was also damaged. A small part of the ground floor of a third property was also damaged. There were no reports of any injuries.
The Brigade's fire investigators believe the fire was accidental and caused by a cigarette igniting rubbish on a decked area.
A London Fire Brigade spokesperson said: "If you're a smoker it's absolutely vital you ensure your cigarette is stubbed out properly and disposed of carefully.
"Make sure smoking materials are cold before emptying ashtrays.
"If you don't you risk causing a fire that could not only risk your home but also your life."
The Brigade's 999 Control Officers took 14 calls to the fire.
The Brigade was called at 1659 and the fire was under control by 1904. Fire crews from Tooting, Wimbledon, Mitcham, Clapham and surrounding fire stations were at the scene.
Firefighters' smoking safety tips
- It's safer to smoke outside, but make sure cigarettes are put right out and disposed of properly.
- Never smoke in bed, and avoid smoking on arm chairs and sofas – especially if you think you might fall asleep.
- Take extra care when you’re tired, taking prescription drugs or if you’ve been drinking alcohol.
- Use proper ashtrays, which can’t tip over and stub cigarettes out properly.
- Don't balance cigars or cigarettes on the edge of an ashtray, or anything else – they can tip and fall as they burn away and cause a fire.
- Don’t leave lit pipes or cigarettes unattended.
- Always empty ashtrays carefully. Make sure smoking materials are out, cold and preferably wet them before throwing into a bin – never use a wastepaper basket.
- Keep matches and lighters out of children’s reach, and buy child resistant lighters.
- Never smoke if you use healthcare equipment like medical oxygen or an air flow pressure relief mattress. If you use paraffin-based emollient creams, ask for non-flammable alternatives instead.
- Consider additional safety measures such as fire retardant bedding or nightwear.
