Police sources said that Vaishnavi, a resident of Mathura Nagar locality, had a dispute with her husband Kallu over mobile phone in the afternoon.
"After Kallu left the house Vaishnavi first administered some poisonous substance to her daughter Vaishali (6) and son Chhotu alias Abbu (2) and later consumed the same," they said.
Police sources said that when their condition deteriorated the family members informed Dial 108.
"The trio was taken to the district hospital where doctors declared Vaishnavi and Vaishali dead. Chhotu has been referred to Jhansi medical college in serious condition," they said.
(With UNI inputs)