It is suspected that they died after inhaling the toxic carbon monoxide gas generated by a hot 'tandoor' (earthen stove) kept in the room, Sabalgarh police station in-charge Ashish Rajput said.
Carbon monoxide is generated when there isn't enough oxygen during the burning process.
The victims were identified as Sachin Jatav, Ramroop Jatav and Chiku Jatav.
"These boys had gone to Sabalgarh with a cook, as his helpers. The cook had been hired for a wedding. After the work the boys went to sleep in the room. They were found dead in the morning," he said.
"However, the exact cause of deaths would be known after the autopsy report comes. A police team has reached the spot and sent the bodies for autopsy. We are carrying out detailed investigations," he added.