According to the preliminary investigation, the four girls identified as Deepa, Sankari, Monisha and Revathi took to the extreme step allegedly after their teacher scolded them and asked them to bring their parents to the school for a briefing about their academic performance.
The four students, police say, skipped their classes on Friday.
"We are investigating. A few parents and local people say the teacher had summoned the parents," a senior police officer P Pakalavan said.
The bodies of three students have been fished out from the 65-ft deep well by the fire and rescue services personnel. Deep divers from the NDRF searched the fourth body.