Six people have been taken to hospital after an explosion destroyed a shop in Leicester.
Police declared a "major incident" after reports of a blast in Hinckley Road just after 19:00 GMT on Sunday.
A police spokesman said: "At this stage there is no indication this is terrorist related."
Two of the six in hospital are in critical condition and the others are "walking wounded", said the University Hospitals of Leicester NHS Trust.
Carlisle Street and part of Hinckley Road have been closed and people are being asked to avoid the area. Electricity has been cut off for a number of properties.
Emergency services remain at the scene and Leicestershire Police said the "search and rescue operation" would continue throughout Monday.
Angel Namaala lives opposite the shop and told the BBC she heard "this big thud, like an earthquake".
She said: "The building had gone down and people were trying to help where they could by taking the bricks off. But the fire was getting bigger and bigger so people were told to leave the scene."
She said she and others helped a boy, believed to be aged about 15, who was hurt in the blast.
"He was in there when it happened. I think he was in the flat above the shop. We were keeping him warm and assuring him he'd be OK and the ambulance would be there," she added.
"Someone was with him already bringing him to the road so I stopped and gave him my coat. And other neighbours gave him blankets to cover himself."
Six fire engines were sent to the scene and a fire service spokeswoman said the property was a two-floor building with a loft conversion that had suffered a "pancake collapse".
Leicestershire Police said: "The cause of the explosion will be the subject of a joint investigation by the police and Leicestershire Fire and Rescue Service."
Thanks for all your good wishes. Fire crews continue to search the debris pile and fight fire. Conditions are arduous on a bitterly cold night but their efforts continue unabated alongside @EMASNHSTrust and @leicspolice— Andrew Brodie (@LFRSABrodie) February 25, 2018
All of the casualties have been taken to Leicester Royal Infirmary and people have been asked not to attend A&E unless "absolutely necessary".
Witnesses said the shop was formerly a Londis but recently became a Polish supermarket.
At the scene, BBC reporter Caroline Lowbridge
Looking down Hinckley Road, past the cordon, there's a smoking gap where the shop once stood.
It exploded with such force that glass and debris were scattered across all four lanes of the dual carriageway.
It's a few hours since the blast, but the air is still thick with smoke.
Earlier, dozens of onlookers gathered - many with scarves over their mouths, or jumpers pulled up, to avoid breathing in fumes.
Witnesses said the destroyed shop had flats above it, and at least one of those injured is thought to have been a resident.
BBC journalist John Alexander said the emergency services had cordoned off about 60 houses in the area.
"I live about 80 yards away from where it happened," he said. "I felt a tremor, what felt like an earthquake shock and I heard a very low boom that sounded like a very, very fast release of pressure.
"I thought my house was going to fall down on top of me and all my neighbours have said the same thing."
Harish Pattni was in a pizza shop six doors down when the explosion happened.
He said: "I've never experienced anything like this. It sounded like those big, loud boom speakers that people have in their cars, real vibration. The bass sound was so loud that it shattered the car windows.
"The flames started more or less upstairs so I thought it must be something to do with upstairs, the flats.
"My immediate worry was when I saw the floorboards, all the wood on the floor level, I thought there must be people in the shop trapped."
| Major Incident |— LeicestershirePolice (@leicspolice) February 25, 2018
19:19 |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.
East Midlands Ambulance Service said that crews from the West Midlands and Yorkshire had responded to other 999 calls near the border while it dealt with the incident in Leicester.
Did you witness what appears to be a big explosion in the Hinckley Road area of Leicester? You must stay safe when you send any pictures to: email@example.com.
You can also contact us in the following ways: