Four people are in a critical condition in hospital after a suspected explosion destroyed a shop.
Police declared a major incident after the blast in a street in Leicester on Sunday night.
Video taken at the scene shows flames billowing into the night sky.
One clip appeared to show emergency services rushing to help someone close to what is believed to be a convenience store engulfed in flames visible from a distance.
The building appears to have stood next to a shop called TJ's Takeaway.
All four casualties were been taken to Leicester Royal Infirmary, East Midlands Ambulance Service said.
A hazardous area response team and ambulance crews remain at the scene in Hinckley Road in the west of the city, it added.
Speaking to Sky News, Kat Pattinson who lives on the same road as the fire, said: "We are down the same street - about 500 metres from where the blast has taken place and our whole house shook.
"We checked on our children first and foremost and then we went outside.
"There is just an awful lot of smoke here at the moment and the whole area is cordoned off."
She added that the shop on fire is usually open until about 9pm on a Sunday, and has a flat above it.
Leicester Royal Infirmary tweeted: "We can confirm that four patients from the scene have been taken to Leicester Royal Infirmary via @EMASNHSTrust in a critical condition."
Leicestershire Fire and Rescue said at around 7.03pm it received calls from the public who said they had heard a blast on Hinckley Road.
A spokeswoman said six fire engines had been requested and that the incident is currently being treated as a search and rescue operation.
She added that the affected property was a two floor building with a loft conversion that had suffered a "pancake collapse".
Leicestershire Police tweeted: "There has been a major incident on Hinckley Road, Leicester.
"All emergency services are currently dealing with this. Carlisle Street and part of Hinckley Road have been closed. Please avoid the area."