Firefighters were called out to the building on Bingham near Colorado around 11pm. Residents were out before firefighters arrived. One resident did suffer a burned hand and was taken to the hospital.
Firefighters have identified the source of the fire.
"We're not going to call for arson. The occupant admitted he was smoking in bed," said District Chief Wallace Page with the Houston Fire Department. "The preliminary investigation by myself and the nature of the burn in that particular room, we're going to call it as smoking in bed."
Firefighters were able to get the flames under control, but the left side of the duplex was heavily damaged.