Mumbai - Rescuers worked through the night removing the rubble of a collapsed apartment building in India's financial capital of Mumbai where at least 24 people have died and more than a dozen others may still be buried.Fire officer Prabhat Kumar said Friday that 15 injured survivors have been pulled from the debris so far, in addition to the 24 bodies removed.Nearly a dozen others were missing and feared trapped beneath the huge mound of broken concrete slabs and twisted steel girders.Rescuers used earth-moving machines to lift concrete slabs and cement blocks as they searched for survivors.The rickety 117-year-old, five-story building in congested Bhendi Bazaar in south Mumbai had been declared unsafe to live in six years ago, but people continued to stay there.READ: Mumbai building collapse kills 18 after heavy rainsRescue effortsThe residents of an adjacent building were advised to leave after it developed cracks.The building had housed nine families in apartments above a first-floor nursery school, but the collapse on Thursday morning occurred before the toddlers had arrived for the day, police said.Nearby resident Amina Sheikh tightly held her 4-year-old grandson's hand as they watched the rescue efforts from a safe distance."This is my grandson. He used to go to school in that building," she said, tearfully pointing at the rubble.She had been getting the boy ready for school when she heard a loud boom and saw the building had crashed down. It was "an hour before his class began. That's why my grandson's life was saved," she said.It was the first major building collapse after Mumbai recorded 315mm rainfall on Tuesday August 29, the city's highest since 2005.Thousands of buildings in Mumbai are more than a century old, their foundations weakened by years of heavy monsoon rains. The collapse of a four-story building in the city's suburb of Ghatkopar in August killed 17.Building collapses are common in India during the monsoon season, which is June to September.High demand and lax regulations encourage some builders to use substandard materials or add unauthorised extra floors.Property prices and rents in Mumbai are among the highest in India as the city has expanded in the past five decades.