Smoke alarms alerted five people to a blaze in flats on Dyche Road, Sheffield.
The people escaped the complex before Central and Lowedges firefighters arrived to tackle the blaze in a ground floor flat. Crews left just before 2am.
The fire was caused by smoking materials accidentally being dropped onto a bed. A man in his 30s had been inside the flat involved in the fire but was unharmed.
A man in his 50s from a neighbouring flat was suffering from the effects of smoke inhalation, but did not need to attend hospital.
People are reminded never to smoke in bed and to discard of ashes safely in a metal bin.