The deceased were identified as Mahendar, Govind and Dharmendra and all were in the age group of 45 to 50 years, police said.
It was not immediately clear as to how the factory chamber started emanating poisonous gas as it only contained the mixture of spices, vegetables and water, they said.
Mahendar slipped into the chamber and the other two brothers went inside to save him, but all the three were affected by the poisonous gas and fell unconscious.
By the time their bodies were retrieved, they were dead, police said.