text: About 70 people were injured and many are feared trapped beneath the seven-storey bloc in Thane after the incident on Thursday evening.
  Building work was going on even though four floors were already occupied. A search for survivors is continuing.
  Building collapses are common with poor construction practices often blamed.
  By Sameer HashmiMumbai business reporter
  The building collapse underlines the issue of illegal construction in India.
  Police say the builder of the high rise used sub-standard construction material and did not possess an occupation certificate.
  There are hundreds of similar  illegal high-rises in the Mumbai region. Due to a high population growth, there is always demand for cheap housing. And homes in illegal buildings sell at a lower price compared to those in legal ones.
  Activists also allege that unscrupulous builders often pay hefty bribes to authorities who turn a blind eye to these illegal structures and do not take any action against the builders.
  The authorities now say they are searching for the officials who were supervising the building works.
  The BBC's Sameer Hashmi, who is at the scene of the incident, says rescue workers are still trying to clear the debris.
  Most people living in the building are from the low-to-middle income groups, our correspondent adds.
  Witnesses say the construction of the building started just six weeks ago and in that time seven floors were built rapidly and the eighth floor was under construction.
  Even though the construction was incomplete, the builders had allowed families to move in, our correspondent adds.
  On Thursday evening a section of the building collapsed, bringing the entire structure down, police said.
  Rescue efforts continued throughout the night and dozens have been injured.
  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.
  One witness, named only as Ramlal, said the building appeared to tilt before quickly collapsing.
  "The building collapsed like a pack of cards within three to four seconds," he said.
  In pictures: Mumbai building collapse
  Schoolgirl Hasina Shaikh, who had lived with her family on the fifth floor, said she was lucky to be still alive.
  "I had just returned from school and was changing when the building started shaking and came down on us," she told Mumbai's DNA newspaper.
  "When I regained consciousness later, I was in the hospital."
  In other recent incidents
target: At least 45 people have died, including 15 children, after a building being constructed illegally collapsed near the Indian city of Mumbai, police say.