Police in southern India detained two construction company directors as rescuers using gas cutters and shovels searched for dozens of workers believed buried in the rubble of a building that collapsed during monsoon rains.
It was one of two weekend building collapses that killed at least 22 people.
The 12-storey apartment structure the workers were building collapsed while heavy rains and lightning were pounding the outskirts of Chennai, the capital of Tamil Nadu state.
Police said 31 construction workers had been pulled out so far and the search was continuing for more than a dozen others.
Four of the workers died on the spot and another seven succumbed to injuries in hospital, said police officer George Fernandes.
Fourteen workers remained in hospital while six others were discharged, Mr Fernandes said.
Two directors of the construction company, Prime Sristi, have been detained for questioning as authorities began investigating the collapse.
Balaguru, one of the builders, said the structure collapsed possibly due to the impact of lightning.
“Usually, once the construction gets over we install the equipment to prevent the building from a thunder strike. It was nearing completion,” the Press Trust of India news agency quoted Balaguru, who uses one name, as saying.
Nearly 300 police and fire service workers worked overnight, looking for survivors in the debris. They used gas cutters, iron rods and shovels to reach those trapped in the rubble, after cranes lifted concrete blocks to clear the way for the rescuers.
“Removing debris is a major challenge. It may take two to three days to clear the rubble,” said SP Selvam, who is heading the rescue operation.
Earlier yesterday, a four-storey, 50-year-old structure toppled in an area of New Delhi inhabited by the poor. Eleven people died and one survivor was being treated in a hospital, said fire service officer Praveer Haldiar.
Most homes in that part of the capital were built without permission and using substandard materials, police officer Madhur Verma said.
The Press Trust of India news agency said the New Delhi collapse was triggered by construction work on an adjacent plot.
Building collapses are common in India, where high demand for housing and lax regulations have encouraged some builders to cut corners, use substandard materials or add unauthorised extra floors.
In April last year, 74 people were killed when an eight-storey building being constructed illegally in the Mumbai suburb of Thane in western Maharashtra state caved in. It was the worst building collapse in the country in decades.