Six houses and several livestock were also burnt in the explosion that occurred in the underground pipeline of the public sector Assam Gas Company Limited near Singlijan Tea Estate under Moranhat police station, Sibsagar Superintendent of Police Debajit Sarma told PTI.
The high density LPG pipeline exploded, killing the three persons and caused severe burn injuries to seven.
All the injured were admitted at the Assam Medical College Hospital in neighbouring Dibrugarh district, he added.
Another person identified as Michael Sabar (30) received 98 per cent burn injuries and his wife Jyoti (23) died in hospital.
The house of one Durga Baraik (42) caught fire and he along with his daughter Menoka (18) sustained burn injuries, while his wife Marina (35) received 95 per cent burns, Sarma said.
Fifty five-year-old Surya Sahu was also injured when his house was caught fire. The blaze spread to the house of his neighbour Ramesh Sahu burning it down along with his livestock and bamboo grove in his compound, he said.