Four people have died after an explosion at a property in Leicester, a city in the English midlands, on Sunday night, Leicestershire police have confirmed.
Emergency services were called to the "major incident" in the U.K. city's Hinckley Road shortly after 7pm.
Four more people were rushed to hospital, East Midlands Ambulance Service NHS Trust said, one with serious injuries.
Authorities have not ruled out more people being trapped under the collapsed building.
Police said there is no indication that the incident is terrorist related, but have yet to confirm the cause.
the police statement said: "It is a search and rescue operation at this time, as we try and find the whereabouts of people who are still outstanding – so if anyone is worried about their family members, please contact us."
Emergency services, including a hazardous area response team and ambulance crews, remain at the scene.
Parts of Hinckley Road has been closed off, while businesses and homes in the immediate vicinity have been evacuated.
Electricity to a number of homes was affected by the incident, and a cordon was put in place, but no neighbouring properties were evacuated overnight.
Matt Cane, police group manager, said: "Crews have worked through the night, alongside partner agencies, as they continue to search the scene in order to try and locate any further survivors or casualties."
A spokesperson for the Leicestershire fire and rescue service said six fire engines had been requested, and the fire has yet to be fully extinguished.
People are being urged to inquire at hospitals only if "absolutely necessary".
The fire and rescue service spokesperson said: "This is a search and rescue at the moment. It is unknown if people are injured or trapped."
She added that the affected property was a two-floor building with a loft conversion that had suffered a "pancake collapse".
Pictures and videos posted on Twitter showed flames leaping into the sky above the city.
It is believed that a convenience store and a house were destroyed in the blast.
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.
The building appears to have stood next to a shop called TJ's Takeaway.
Leicester police said in a statement: "The cause of the explosion will be the subject of a joint investigation by the police and Leicestershire fire and rescue service.
"We would ask that the media and public do not speculate about the circumstances surrounding the incident, but at this stage there is no indication this is terrorist related."