The underground gas pipeline of the public sector gas company burst at 3.30 am at Singlijan Tea Estate under Moranhat police station.
Jyoti Sabar died on the spot and Michael Tapno (30), Paras Sarma (28) and her husband Bhasan Sarma (35) succumbed to their injuries in hospital, the spokesman said.
Six houses and several livestock were burnt in the explosion, Sibsagar superintendent of police (in-charge) Debajit Sarma told PTI.
The injured persons were taken to the Assam Medical College Hospital in neighbouring Dibrugarh district. Two persons have been released and four injured were undergoing treatment, the spokesman added.
Bhasan and Paras Sarma's two children Akash (7) and Hemanta (9) received 99% burn injuries when their house was burnt to cinders, the SP said.
The house of one Durga Baraik (42) also caught fire and he along with his daughter Menoka (18) had 7% burn injuries, while his wife Marina (35) sustained 95% burn, the SP said.
Fifty five-year old Surya Sahu sustained 30% burn injuries when his house also caught fire that spread to the house of his neighbour Ramesh Sahu burning it down along with his livestock and bamboo grove in his compound.