A fourth person has died after an apparent gas explosion in a duplex on the Pine Ridge Indian Reservation.

Tribal Councilman Richard Greenwald confirmed the fourth death. He says the victims were an elderly man and an elderly woman in one side of the duplex, and two young women in the other side.

Authorities have not released the names or ages of the victims.

Tribal spokesman Kevin Yellow Bird Steele says the explosion in the town of Pine Ridge occurred Thursday afternoon. Several people injured in the blast were transported to surrounding hospitals.

Steele says tenants in the duplex smelled propane gas and were searching for a leak before the explosion.