At least seven migrant labourers from Bihar are feared dead after a massive boulder collapsed at a stone quarry in Bengaluru South taluk early on Thursday, trapping several workers beneath tonnes of rock and debris. Rescue teams fear the death toll could rise as operations continue at the site.

The incident occurred around 5 am at the Kaveri Crusher unit in Madapatna village under the jurisdiction of Tavarekere Police Station.

According to preliminary information, around 20 labourers were working nearly 40 feet below the surface when a huge rock suddenly gave way and crashed onto them. The workers were carrying out quarrying operations after blasting had reportedly been conducted at the site a day earlier.

Police said the identities of the deceased are yet to be confirmed, but the victims are believed to be migrant workers from Bihar. Some of the injured are reportedly from Karnataka.

At least five workers sustained serious injuries and were rushed to RR Hospital for treatment. Several heavy boulders also crushed earthmoving machinery and other excavation equipment during the collapse.

Eyewitnesses said the workers had no warning before the boulder came crashing down.

"The incident took place at around 5 am when more than 15 to 16 workers were on duty. Some managed to run to safety, some were injured, and others were trapped beneath the boulder. It did not appear that the boulder fell because of the blasting itself; it collapsed suddenly while the workers were carrying out their routine work," an eyewitness said.

Another worker, Vinod, who narrowly escaped the collapse, described the horrific scene.

"When the boulder collapsed, many workers were trapped beneath it. Some lost their legs, while others lost their hands. We could do nothing to rescue them. I was operating a Hitachi excavator about 10 metres away. The victims were drilling at the quarry and did not notice the boulder above them," he said.

Rescue teams, along with police and emergency personnel, are continuing efforts to clear the debris and locate those feared trapped. Officials said the bodies of the deceased had not been recovered till the latest reports.

Senior police officers and district administration officials have reached the site to supervise the rescue operation.

Authorities said the quarry possessed the required lease, licences and permissions for quarrying operations, including the use of explosives. However, the exact cause of the collapse remains under investigation.

Police have registered a case and launched a probe into the incident, while rescue operations continue amid fears that more workers may still be buried beneath the rubble.

With IANS inputs