The fire happened on Legion Street near Brewster, just after midnight.
Officials said a firefighter discovered the fire while returning to the station from another scene.
"One of the chiefs noticed smoke and fire coming from this location," Deputy Chief Douglas Harrison said. "They proceeded over here and called dispatch for a working fire."
At least 4 units in part of the complex caught fire, according to Harrison.
SEE ALSO: 10 units damaged in north Houston apartment fire; crews working to put out hotspots, HFD says
"They started trying to check the units to make sure everybody got out," he said.
Originally, HFD said they were searching for someone who was reported missing after the fire, but said everyone was accounted for.
Harrison said crews did rescue a woman and her dog from the building.
"She had, at minimum, smoke inhalation," He said. The woman was transported to the hospital for treatment. The dog was treated and is expected to be OK.
It is unclear what started the fire at this time.
For news updates, follow Chaz Miller on Facebook, X and Instagram.