A 30-year-old woman and her two minor daughters were killed by her sister-in-law following a dispute over their ancestral land in the district, police said on Monday.
Asha Tyagi and her daughters Pari, 5, and Ananya, 3, were first served poisoned milk and then smothered on Sunday, the police said.
The incident was reported to police by Asha's husband Rameshwer. He alleged that her elder sister Geeta, her son Vikrant and daughter Priyanka killed his wife and daughters, Senior Superintendent of Police Kalanidhi Naithani said.
The bodies had strangulation marks, the SSP said, adding that the police have recovered a steal utensil in which milk was boiled and tablet of sulfas from the victims' room.
Vikrant has been arrested, while her mother and sister are at large, he said.