BILLINGS, Mont. (AP) — An explosion at a Billings residence has sent three people to the hospital.

The Billings Gazette reports three men appeared to have suffered burns in the explosion at 8:30 a.m. Wednesday in a residence on the city's south side.

Fire Chief Paul Dextras says firefighters extinguished a small fire, but the structure is so damaged it is not safe.

The newspaper reports the back wall of the house appeared to have been knocked off the foundation and upstairs windows were blown out.

The cause of the explosion and fire are under investigation.

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