One person is in a critical condition following a suspected gas blast at a block of flats in Wigan.
Police were called to a three-storey block of flats and found the top two flats had collapsed into the ground-floor flat.
A total of four people were taken to Wigan Royal Infirmary with burns, one of whom was in a critical condition.
Police did not think anyone was still trapped at the scene but a full search of the site had yet to be carried out.
John Aspinall, from Greater Manchester Fire and Rescue, told BBC News 24 they were looking at the possibility that there had been "some form of gas explosion".
He added: "The search and rescue teams are making an entry to the scene but it is painstakingly slow."
It happened in Blake Close, Worsley Mesnes. People at the scene were treated for smoke inhalation and shock.
A fire was brought under control and the gas supply to the building isolated.
