At least four people were killed and four more injured when a blast destroyed a convenience store and a home in the central English city of Leicester on Sunday, British police said.
The blast ripped through the building at about 1900 GMT, turning a shop on the ground floor and a two-story apartment above it into rubble.
"There are four confirmed fatalities at this stage and a number of people still undergoing treatment in hospital," Leicestershire Police Superintendent Shane O'Neill said.
"We believe there may be people who have not yet been accounted for and rescue efforts continue in order to locate any further casualties."
He said there was no immediate indication that the explosion was linked to terrorism. Pictures and videos showed flames leaping into the sky from the site, with rubble strewn across the street.
"We heard this massive explosion, the shop window six doors away vibrated and we thought it can't be a car accident, it didn't sound like a crash," local resident Harrish Patni told Sky News. "We came outside and there was a big cloud of smoke, bricks all across the road."
Local media reported that the shop was believed to be a Polish grocery store.
Investigators were working to determine the cause of the blast, O'Neill said, while specialist rescue teams including search dogs were on the scene looking for any more survivors and further casualties.