Six gaurs, including a calf, were searching for water when it fell into the well at a farm in Pattinampatti village, four days ago.
Three gaurs sustained fracture and died while three others were rescued, forest officials said, adding, the wild animals are protected under the Wildlife Act.
The farm owner came to know about the animals only after foul smell of decomposing carcasses emanated from the well. Forest ranger P Bagavathy and other department personnel used earth movers to enable the gaurs to climb up the well and run into the forests.
Two female gaurs and a male were healthy and ran away while a calf and two adult gaurs died, the official said.
The carcasses were buried after post mortem.