British police said on Sunday there was no indication a reported explosion and building collapse that critically injured at least four people in Leicester, a central English city, was linked to terrorism.
"The cause of the explosion will be the subject of a joint investigation by the police and Leicestershire Fire and Rescue Service," local police said in a statement.
"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."
The reported explosion and building collapse occurred Sunday evening on a stretch of road containing commercial and residential properties close to the city centre.
Businesses and homes in the immediate vicinity were evacuated and those impacted were taken to a local police station as a temporary measure, police said.
Meanwhile, the electricity supply to a number of properties in the area has been cut while emergency services deal with the incident, it added.
The Fire and Rescue Service said it received calls shortly after 7:00 pm (1900 GMT) from the public reporting an explosion and a building fire.
It immediately dispatched six fire engines, a spokeswoman said.
"We were en route when the police called to say a building had collapsed," she added.
Additional specialist search and rescue units were then dispatched, including a search and rescue dog, according to the spokeswoman.
"We've got no indication of what the cause is at this moment," the spokeswoman said.
Four people have been taken to hospital following the incident, the ambulance service said.
City hospital the Leicester Royal Infirmary said it was treating the four patients, who were "in a critical condition".
It advised people to only attend its accident and emergency department "if absolutely necessary".
The fire service spokeswoman also said representatives from gas and electric provider companies were in attendance at the scene, under routine procedures.
Pictures and videos posted on social media showed a property engulfed in flames visible from a distance, with rubble and debris scattered around.
Graeme Hudson told AFP he lives close to the scene and felt the blast.
"It was very scary," he said. "I live five minutes away... but my house shook. I went out and saw massive smoke and big flames.
"I quickly went out to see what's happened," he added. "(I) didn't stay for long there because (I felt) unsafe for my 11-year-old son."