A septic tank explosion in Gazipur's Tongi area left a teenage boy dead and his younger sister critically injured on Sunday night.

The deceased was identified as Habibullah, 19, son of Ruhul Amin from Baherchar Kadamtali village in Shariatpur district, said Iskandar Habibur Rahman, officer-in-charge of Tongi West Police Station.

The incident occurred around 10:00pm on the first floor of a rented house in Mollapara area of North Auchpara.

Quoting the tenants, the OC said the explosion caused the walls of three rooms, including the washroom, to collapse. Habibullah and Jannati were in one of the affected rooms when the blast occurred.

Neighbours rushed the critically injured siblings to Dhaka Medical College Hospital, where doctors declared Habibullah dead around midnight.

His sister Jannati, 13, was undergoing treatment at the hospital.

Shahin Alam, a senior officer of Tongi Fire Service, attributed the explosion to the lack of a bypass line in the septic tank.

A case of accidental death has been filed in this regard, the OC added.