At least 6 persons were killed and 40 were injured when an under construction... (Associated Press) 
 
 The building in the Mumbai suburb of Thane caved in Thursday evening, police said. `'All the three floors are sandwiched ... so it's is very difficult for us," he said, adding that rescuers were continuing to pull survivors from the wreckage. At least four floors of the planned eight-story building had been completed and were occupied. It is not yet clear what caused the collapse, but police inspector Digamber Jangale told the BBC it appeared to be due to the use of substandard building material. Police said a case had been registered and an inquiry had begun and that they were searching for the builders to arrest them. Building collapses are common in India as builders try to cut corners by using poor quality materials, and multi-storied structures are built with inadequate supervision. The massive demand for housing around India's cities and pervasive corruption allow builders to add unauthorized floors or build entirely illegal buildings. In other recent incidents 
 
 At least 13 people died when part of a half-constructed building collapsed in the Wagholi area of Maharashtra in December 
 
 At least six people were killed when a building collapsed in Pune city in Maharashtra in September
– At least 41 people have been killed after a building collapsed near Mumbai, the AP reports. More than 50 have been injured, and more could be trapped. At least 11 children were dead, officials said, with more than 20 people missing amid rescue efforts. The seven-story building was in the midst of illegal construction, the BBC reports, with four floors already occupied. The casualties were mostly construction workers who'd been staying in the building, said an official. "The building collapsed like a pack of cards within three to four seconds," said a witness. The disaster occurred as workers attempted to build an eighth floor, the AP notes. Building collapses are frequent in India thanks to weak materials and procedures, reports the BBC. High rises have been increasing in step with population increases, but they're often built without necessary safeguards and licenses. In this case, a witness said, "they made an eight-story building [out] of what was supposed to be a four-story building." Police intend to arrest the builders.