At least 15 workers have been killed and at least 50 are feared trapped after a building collapse in the Indian state of Chhattisgarh, officials say.
Officials say that a chimney caved in on more than 100 workers during construction work at a thermal power plant.
The accident happened in the town of Korba, 200km (124 miles) from the state capital Raipur.
The plant is being built by Bharat Aluminium Co Ltd (Balco).Balco is a unit of London Stock Exchange-listed Vedanta Plc, whose business activities are mostly in India.
"It's a massive accident," Ratanlal Dangi, district superintendent of police, told the Reuters news agency.
"We have launched a rescue and relief operation to save about 50 workers and engineers trapped inside."
Chhattisgarh state police spokesman RK Vij told the AFP news agency that there were "over 100 labourers working on the site when the chimney fell" and that police believed that 60 to 70 more people could be still trapped under the debris.
"There is chaos at the plant. Labourers are helping the rescue team to pull people out of the debris," Mr Vij said.
Television footage showed desperate rescue efforts under way to bring out those trapped by the chimney's collapse as family members waited anxiously for news of relatives.
"Seven injured people have been brought to hospital," Balco General Manager BK Srivastava told AFP."
A chimney of 275 metres was being constructed, 100 metres were already completed. There was heavy rain and lightning when the incident occurred," he said.
Chhattisgarh Chief Minister Raman Singh said a judicial investigation had been ordered into the accident.
A recent report by the UN's International Labour Organisation said that nearly 50,000 Indians die from work-related accidents or illness every year.