The incident came to light on Sunday evening in Gyan Khand area of Indirapuram locality bordering Delhi.
Superintendent of Police, City, Shlok Kumar from the spot said Sumit Kumar killed his wife Ashnu Bala (32), son Permesh (5), and twins Akriti (4) and Aru (4) by administering them sleeping pills in some liquid. Before fleeing, he informed his brother-in-law that he has killed his wife and children and was going to kill himself. He is yet to be traced.
The forensic team's primary investigation suggests the incident occurred early on Sunday but came to light at about 8 p.m., the SP said, adding that the bodies have been sent for autopsy and investigations are on.