Firefighters were called to Wardley Square in Tyldesley at 2.30am on Monday to tackle a blaze in a flat.
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A man had been smoking in bed and gone to another room, where he fell asleep, when the bed caught fire.
He left the flat as the fire developed and it caused a lot of damage to his property.
Crews from Atherton, Farnworth and Agecroft fire stations attended and spent three hours there.
Ian Gardner, watch manager at Atherton fire station, said: "Unfortunately it totally smoke-logged the flat above his, so we had to break into that one as well. That was empty, but we had to check and clear the smoke.
"The smoke affected two other occupiers in a nearby flat and they had to receive medical treatment with oxygen."