Seven workers from Bihar were killed after a massive rock collapsed at a stone quarry in Bengaluru on Thursday, police said.According to police, the tragedy occurred in the early morning at Madapattana in Bengaluru South Taluk.The victims, all daily-wage labourers employed at a stone crusher site, were trapped beneath the fallen boulder and died on the spot, according to police.Police said the accident occurred while the workers were engaged in quarrying operations.The injured were shifted to a private hospital for treatment. The exact number of those injured was being verified, though initial reports indicated that several workers sustained injuries.Rescue personnel and police rushed to the spot and launched operations following the collapse.The area was cordoned off as officials began clearing debris and searching for any other workers who may have been trapped.One of the labourers said there were about 18 workers at the site. A huge rock fell from about 40 feet on the workers.Police said the deceased were all natives of Bihar and efforts were underway to inform their families.Further investigation has been taken up to ascertain the cause of the rock collapse and whether there was any negligence or violation of safety norms at the quarry, police added.