Emergency services were called on Sunday to reports of a blast in the Hinckley Road area in Leicester. They were conducting a search and rescue operation at the scene, BBC reported.
Carlisle Street and part of Hinckley Road have been closed and police are asking people to avoid the area.
Six fire engines were at the scene, Leicestershire Police said. Pictures showed flames rising from a building.
A Leicestershire Fire and Rescue Service spokeswoman said: "This is a search and rescue at the moment. It is unknown if people are injured or trapped."
The affected property was a two floor building with a loft conversion that had suffered a "pancake collapse", she said.
"You can still see the smoke coming, and the emergency services. There are few shops there and it is surrounded by houses," she added.
She said that it was worrying being so close to the explosion and she hoped the authorities would determine its cause.
Pictures and video shared on social media appeared to show a shop engulfed in flames and the blaze visible from a distance.