Sarita, 30, first drowned her six-year-old daughter Parihar in a washing machine tub and then drowned her 11-month-old son Rudrakhsa in a water bucket, before hanging herself from the ceiling fan on the first floor of their two-storey house in east Delhi's Mandawali area, said a police officer.
Her elderly mother-in-law was on the ground floor at that time, police said.
Sarita was depressed due to a family dispute. She had a heated argument late Tuesday with his husband Devendra Yadav, who works in a export house at Patparganj.
Her husband discovered the bodies. He was questioned, said police.
They got married in 2005. Rudraksha's birthday was in this week and he was going to complete the age of one year, a neighbour said.
"Today (Wednesday) Devendra Yadav went his office without the breakfast. In the noon, Sarita called Devendra and said that she is going to kill herself," said the officer.
On returning from office, Yadav found the door of the house bolted from inside. When no one answered the door despite repeated knocks, he broke in and found the three bodies.
"It appears like suicide as the door was locked from inside but we are looking at all the angles," the officer said.