At least four people were killed in an explosion and fire at a three-story building in the central English city of Leicester, British police said on Monday. "At this stage, there are four confirmed fatalities and four people remain in hospital, one with serious injuries," Leicestershire police said in a statement about the blast on Sunday evening. Officers said there was no indication the explosion was related to terrorism but the cause had yet to be determined.   Firefighters worked through the night to control the blaze, which tore through the building in a residential area west of Leicesters city center, turning a shop on the ground floor and a two-story apartment above it into rubble. Police Superintendent Shane ONeill warned that the toll may yet rise further.  "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. Pictures and videos posted on social media showed a property engulfed in flames, with rubble and debris scattered around. "It was very scary," local resident Graeme Hudson told AFP. "I live five minutes away... but my house shook. I went out and saw massive smoke and big flames." "We heard this massive explosion, the shop window six doors away vibrated and we thought it cant be a car accident, it didnt sound like a crash," another local resident, Harrish Patni, told Sky News. "We came outside and there was a big cloud of smoke, bricks all across the road."