Fire brigade officials managed to plug the leakage in around two-three hours.
Leakage started from the gas tank in the morning, initial investigations suggests that the lid of the tanker was broken by the monkeys in the area, police said.
Around twelve persons including two plant workers fell unconscious, some people complained of nausea, breathlessness and burning sensation in their eyes.
Affected persons were rushed to the nearby hospital and were discharged after first-aid, police added.
The gas plant in Khorli village supplies ammonia to nearby hospitals, ice factories and meat plants.