Seven workers died on the spot, and six others who sustained serious injuries have been shifted to the hospital for treatment. Express Photo/Special ArrangementAt least seven migrant workers were killed and several others are feared trapped after a massive boulder collapsed at a stone quarry on the outskirts of Bengaluru Thursday morning.The police said the accident occurred around 7.30 am at the Kaveri Jelly Crusher in Bengaluru South taluk, when labourers were engaged in routine quarrying operations. They said the boulder fell on the spot where workers were operating machinery, leaving them with no time to escape.Seven workers died on the spot, and six others who sustained serious injuries have been shifted to the hospital for treatment.“Seven people have been killed and six others injured so far,” a senior police officer confirmed, adding that the death toll may rise as rescue operations are still in progress and some workers are feared trapped under the debris.Migrants labourersAccording to the police, around 15 to 20 workers, mostly migrant labourers from Bihar and Karnataka’s Yadgir district, were present at the site when a huge rock mass suddenly gave way and crashed onto the work area.The deceased were daily wage labourers who were reportedly living in makeshift accommodation near the crusher unit.Also Read | 2 labourers die in mudslide at building site in Bengaluru; second incident in a monthPersonnel from the Tavarekere Police Station and senior officers rushed to the scene soon after the accident and launched search-and-clearance operations.Story continues below this adAccording to the police, the quarry belongs to a man identified as Anandaswamy, who has been taken into custody for questioning.They said a case is yet to be registered, and the exact cause of the rock collapse is under investigation.