Devyani, 30, a resident of Solai Nagar, committed self-immolation at her house, around 9 a.m. on Tuesday, when she was alone with her 5-year-old daughter, Vinodhini.
The daughter said her mother pushed her out of the house, before setting herself on fire.
The thatched hut, where the two were staying, was almost gutted before the neighbours could raise an alarm.
Devyani had been estranged from her husband, Sengani, said V. Loganathan, sub-inspector of Solai Nagar police station.
“We are trying to locate her husband,” said Mr. Loganathan.