The accused has been booked under IPC sections 302 (murder) and 307 (attempt to murder).
A man, who had set a 40-year-old woman on fire, with whom he was having an extra-marital affair, in Maharashtra, was arrested from Uttar Pradesh.
The accused, Jalaluddin Khan (55), had set afire the woman, Sangita Suresh Devre, her married daughter and infant granddaughter at her home in Panchavati locality on Monday after an argument.
While the nine-month-old infant and Ms Devre died, the third victim, who suffered 80 per cent burn injuries, was admitted to the Nashik Civil Hospital, where her condition was stated to be serious, Panchavati police station in-charge Madhukar Kad said.
Following the incident, the man, who is married, fled to Aligarh in UP. The Nashik Police managed to trace him and arrested him from Aligarh last evening, Mr Kad said.
The accused has been booked under IPC sections 302 (murder) and 307 (attempt to murder), he said.
Mr Khan was having an affair with Ms Devre for the last one year. They had a heated argument over some issue on Sunday, the official said.
He came to her home past midnight on Monday. Devre's 19-year-old daughter and her granddaughter were also in her home at that time, he said.
Mr Khan poured kerosene on all three, set them afire and fled the scene, the official added.