Rajesh Gulati (32), a vikram driver, who received 90 per cent burn injuries, died in the Coronation government hospital hours after the incident.
In his police statement, Gulati said he had an argument with his wife Monika (24) at his Panditwari residence here following which he strangulated her and their three-year-old son Rishi and set them on fire. After that he tried to commit suicide by setting himself ablaze, they said.
While Gulati's wife and son died on the spot, he was rushed to the hospital.
Further investigations are on, police added.
Incidentally, another Rajesh Gulati, an engineer, had murdered his wife Anupama and cut her bodies into pieces in 2010 here, an incident which had rocked Uttarakhand. Gulati had kept the body pieces in a deep freezer for nearly two months.