Six workers were trapped inside a 300-foot-deep stone quarry in Tamil Nadu’s Tirunelveli district after a giant rock rolled down into the pit of the quarry on Saturday night.

While the police managed to rescue two workers an operation to pull out four others is under way at the quarry near Munneerpallam, Inspector General of Police (South Zone), Asra Garg told journalists.

Fire and Rescue services personnel from Tirunelveli, Thoothukudi and Kannaiyakumari districts have been pressed into service.

A Naval helicopter was flown to the accident site to help in the rescue mission on Sunday morning, but the depth of the quarry was hindering the chopper’s operation. Later, the officials sought the help of professional rock-climbers, who managed to rescue the two workers.

According to police sources, three cranes and three trucks were in the quarry pit when the huge rock came crashing down at around 11.30 p.m.

The soil around the rock could have been washed away in the rain as a result of which it came loose, according to the police.

Efforts were also being made to break the rock to rescue the trapped workers, the police said. Tirunelveli district Collector Vishnu and Superintendent of Police P. Saravanan, were at the spot supervising the rescue operation.