Superintendent of Police Shekhar Koirala of the district police office said Saddham sprinkled petrol on the house before torching it.
Riyaj’s wife Chanda Salmani, 22, her two sons three-year-old Riyajul and 10-month-old Rihan and a daughter Mariyam, 5, were seriously injured in the incident.
After primary treatment at Bheri Zonal Hospital, they have been rushed to the Capital for advanced medical care. At the time of incident, Riyaj was in Dolpa, where he runs a barber shop.
The house was completed destroyed in the fire.
“I had just woken up when he set the house ablaze while all my children were inside,“ said Chanda, adding that she, along with the police and neighbours, rescued the children.
Saddham was trying to flee to India when police nabbed him.
“Primary investigation suggests a dispute over money was the possible cause of the incident,“ said SP Koirala.