About 20 workers, including 14 women, were hospitalised following an ammonia gas leak from a private dairy unit in Andhra Pradesh’s Chittoor district on Thursday night, officials said.

The incident happened at Hatsun Dairy at M Bandapalli village of Poothalapattu block around 9 pm as workers were undertaking welding of the plant at around 9.30 pm. All the affected persons were contract workers and came for the night duty.

The latest incident comes three months after a deadly gas leak near the port city of Visakhapatnam, at a plant operated by a unit of South Korea’s LG Chem Ltd, killed 12 and led to the hospitalisation of hundreds.

Chittoor district collector Narayana Bharat Gupta, superintendent of police Senthil Kumar rushed to the factory to supervise rescue operations.

The reasons for the leakage of the gas were being ascertained, they told reporters late at night. However, the situation was brought under control instantly and all those who had fallen sick were shifted to Chittoor government hospital, they added.

“The condition of three of them is said to be serious, but they are out of danger as they had no other complications. If necessary, they would be shifted to Tirupati hospital for better treatment. They would be under observation for three days,” Gupta said.

The collector said he would order a comprehensive inquiry by the general manager of the department of industries and also the fire department.

State panchayat Raj minister Peddireddy Ramachandra Reddy spoke to the collector and enquired about the incident. He directed that the victims be provided the best medical care.