The blaze erupted at United Breweries Nizam Limited situated on the outskirts of Kothlapur Village under Sangareddy Mandal in the wee hours, Sangareddy rural police station sub-inspector Rajashekar said.
The incident occurred when the workers were cleaning a boiler. Four of them were injured, the officer said.
The three injured were admitted to a local hospital while another one was shifted to Hyderabad for treatment, Rajashekar said.
The fire has been brought under control. A case in this connection has been registered and investigations are underway, he added.