Three people died and over 50 others fell sick as toxic gas leaked from a tanker parked at a chemical factory in Beawar district of Rajasthan, an official said.
He said the factory owner and two others have died.
District collector Mahendra Khadgawat said nitric acid leak at an illegally operated factory in a residential area in Badiya locality led to 53 people falling sick late on Monday night.
The situation was controlled in time, he said.
According to Superintendent of Police Shyam Singh, several people in the vicinity fell sick and were admitted to different hospitals following after inhaling the gas.
He said factory owner Sunil Singhal (47) died on Monday night, while local residents Dayaram (52) and Narendra Solanki (40)died on Tuesday.
Another official also said people in the area were admitted to a local hospital after they complained of breathing problems, heaviness in chest and vomiting.
Two persons, who are in a critical condition, are undergoing treatment at JLN hospital in Ajmer.
The official said people in the area around the factory has been evacuated.
Collector Khadgawat has ordered formation of a committee of officials from Nagar Parishad, revenue department and police to survey factories operating without permit in the district.
