An 18-year-old woman and 23-year-old man were rushed to hospital with suspected broken bones and smoke inhalation following the fire in Edinburgh.
A witness told how she saw the 24-year-old pregnant woman desperately trying and failing to get out of a kitchen window before being led to safety by firefighters.
The incident happened in Murrayburn Green at 2am and, at the height of the blaze, involved 30 firefighters. In all, five people had to be plucked to safety.
After the fire was put out, crews discovered a major gas leak in the flat on the second floor and they had to work with police to evacuate residents from neighbouring properties to safety.
Witness Sacha Carson, 28, said: “I could see the pregnant lady banging on her kitchen window but she couldn’t get out. The kitchen windows only open so far, it wouldn’t open wide enough.
“A fireman went up in a crane and I think he got her to go to her neighbours and got out that way.
“I had to stop watching as I got too panicky. It seemed quite ferocious. The sky was glowing red because of it and there was smoke everywhere.”
David Brown, 39, a neighbour in the adjoining block of flats, described the scene after the couple jumped from the third storey.
“The flames were big, they were coming out of the window and I then I saw two bodies on the ground, a guy and a girl.
“They weren’t so much screaming in pain as moaning and they were greetin as you can only imagine the pain they were in.
A spokeswoman from Lothian and Borders Fire and Rescue Service said: “An investigation into the cause of the blaze will now take place. We would urge people to remember that fire can strike at any time and spread very quickly. Make sure you have a working smoke alarm to alert you if fire does break out. “