The blaze took hold on the first floor of the property in Hinde Street, Page Hall, yesterday afternoon and spread through the building with flames bursting out through the roof.
Firefighters said there are believed to be six family members - three adults and three children - who lived at the property, who were either out when the fire broke out or fled the property shortly after it started. An onlooker told how a friend had seen a woman throwing a burning object out of the window, possibly a curtain.
A large crowd gathered as firefighters from three stations across the city battled to keep the blaze under control. One resident sent in these dramatic pictures and video.
Jonathan Ward, watch manager at Elm Lane Fire Station, said: "They were not at the scene and we understand nobody was injured. They were either away from the property or got themselves out.
"There was no working smoke alarm in the property. If there had been then we may have been alerted a lot quicker and the fire may not have spread through the whole house. Likewise it is a good job nobody was inside.
"This shows how important it is to have a working smoke alarm."
He added: "The fire started in one of the bedrooms. It blew the windows out and spread throughout. It is not believed to be deliberate and we are working on the basis that it was accidental.
"But due to the extent of the damage the cause is still under investigation."
Crews from Elm Lane, Rivelin and Parkway stations were called to the scene at about 2.30pm. Firefighters wearing breathing apparatus used hose reel jets and a specialist aerial platform to put the blaze out. They were at the scene for about two hours.
One resident, who did not want to be named, said a friend called the fire brigade "but he thought the fire would probably be out by the time they arrived.
"The next thing he looked out of the window and there were flames billowing out of the windows."