Firefighters who tackled two blazes in Manchester have said the buildings may have to be partially demolished before they can confirm if anyone was inside.
A number of nearby streets were closed by the fire
More than 120 firefighters were called to tackle the fires on Dale Street in the city's Northern Quarter.
A number of nearby roads, including Newton Street and Dale Street will remain closed until Tuesday morning.
A structural survey of the buildings will need to be done before rescue crews can enter the two properties.
A fire service spokesman could not confirm whether anyone was in the buildings during the fire until safety checks had been made on the structures.
Paul Duggan, from Manchester Fire and Rescue Service, said: "This has been a large scale incident but we now only need 30 firefighters to dampen down the buildings."
He said that he believed that one of the buildings had been under reconstruction before the fire started and that the adjacent building had housed a number of small businesses.
"Until the structural survey confirms that it is safe to enter the buildings we cannot check to see if anyone is still inside," he added.
Traffic is being disrupted on nearby roads and motorists are advised to avoid the area, which is likely to remain cordoned off for about 24 hours
At its height, more than 25 fire appliances, police and paramedics were at the scene.
The alarm was raised at 0555 BST and the incident quickly escalated.
A number of streets including Dale Street, Lever Street, Hilton Street, Newton Street and part of Oldham Road were closed.