The employees were admitted to a private hospital in suburban Charpok this morning and condition of four of them is stated to be serious, police said.
The employees of the firm, located in Charkop, complained of running nose, dry eyes, reddening of eyes and headache after a pest control treatment was done at the firm yesterday, a police official said.
Yesterday, some of the employees experienced discomfort till 5 PM, the closing time of the office. This morning, when they arrived at the office, they complained of similar things and were admitted to the hospital, they said.
"We have recorded the statements of the employees. No case is so far registered in this connection and we are waiting for medical reports of the employees", the officer said.
According to police, concerned company authorities will be questioned.
Police said four of the employees were discharged today.