MUMBAI — Frantic relatives kept up a vigil Saturday at the site of a collapsed apartment building that killed at least 50 people in India's financial capital of Mumbai, as the search for survivors grew bleak. Rescuers found just one person alive during the day. The cause of Friday's cave-in was not known, but neighborhood residents complained of builders using substandard materials — with some expressing fear that their own buildings might also fall down. It was the third deadly building collapse in six months in Mumbai, which like much of India has lax building inspections and corruption that can form a deadly combination. Rudiben Parmar sat with several weeping relatives near the rubble on Saturday, waiting for news of the last of five family members who were in the building. Three – a nephew and two of his children – had already been found dead. The nephew's wife was rescued, but the couple's young daughter was still unaccounted for Saturday morning. Parmer said she didn't know who was to blame for the disaster, but didn't care about anything but learning of all her relatives' fate. “We will be OK once all members of our family are recovered,” she said. The five-story building, which housed workers for the Mumbai municipal government, caved in early Friday morning near Dockyard Road in the city's southeast, trapping dozens of people and launching an intense search mission. Rescuers have pulled 33 people out of the rubble alive since the cave-in, but the searchers have not detected any signs of life recently, said Alok Awasthi, local commander of the National Disaster Response Force. Emergency workers labored for six hours Saturday to free a 50-year-old man who was trapped for more than 30 hours beneath the wreckage with his leg crushed by part of a wall. Rescuers reached him and lifted up the slab of cement using a specialized compressed air-pressure bag, and the man was rushed to a hospital in the afternoon. “We were able to save him, but he may lose his leg,” Awasthi said. The death toll had climbed to 50 by Saturday evening, he said. “We are not finding any more signs of life right now, but we will continue to search until all are accounted for,” he said. The building that collapsed was constructed in 1980, Awasthi said, adding that what caused it to fall down would be determined by an investigation. But local residents complained of substandard materials and corruption as the root causes of such disasters. “There should not be corruption in the building process. They should use best of the materials — then only the buildings will last,” said Sanjay Mayekar, who lives in another apartment building next to the one that fell. Some neighbors said they even feared about the safety of their own buildings. “We can't know that tomorrow it won't be our turn,” said Anupama Shivalkar, who lives in another nearby apartment block. Two other buildings have fallen down in Mumbai this year. At least 72 people died in April when an illegally constructed building fell down, and in June, at least 10 people, including five children, died when a three-story structure collapsed in the city. Across India, buildings falling down have become relatively common. Massive demand for housing around India's fast-growing cities combined with pervasive corruption often result in contractors cutting corners by using substandard materials or adding unauthorized floors. — AP