The force of the blast led to the partial collapse of the three storey block in Blake Close, Worsely Mesnes, and more than 70 fire fighters had to battle for several hours to bring the resulting blaze under control.
More than 36 casualties were evacuated from the flats and two males, aged 26 and 43, were taken to hospital suffering from burns. The 26-year-old is in a critical, but stable condition while the condition of the 43-year-old is serious, but stable. Their injuries are not thought to be life threatening.
Police officers also helped evacuate residents from 36 neighbouring council owned properties.
A joint investigation into the cause of the incident is underway between Greater Manchester Fire & Rescue Team and Greater Manchester Police.