Investigators are looking into what started a fire that killed two people in southeast Houston overnight.

The fire broke out around midnight Thursday at a boarding house on Griggs Road near Calhoun. The facility, which apparently has no windows and only two ways in and out, serves as a home for people with mental and physical challenges.

Firefighters found two people dead just inside the front door. At least one other person deeper inside the building was taken to the hospital for smoke inhalation. Sandra Gooden has been identified by family as one of the victims. She'd lived there for three years.

Officials believe the flames spread through the attic of the shelter, which appears to be an old shopping center.

Those who know the facility say inside it's like a maze.

"I was praying that I'd make it because I was inhaling smoke, and I walk with a walker, but I was without it," said resident Syreta McCullough. "But the Good Lord gave me strength to walk. I ran. I ran. And I made it."

Although the facility does have a fire alarm, it does not have a sprinkler system, and there are no windows on the individual units inside.

HFD confirmed that in 2014 the property owner, Moses Briscoe, applied for a boarding home permit, but an inspector denied it because it didn't meet safety requirements. There's no record of any other permit applications every since. That means it was illegal for people to be living there in the first place.

The City of Houston also reports that an anonymous complain concern the building's safety was called in to 311 in 2015. The Public Works Department passed it on to another department and no one ever followed up.

The cause of the fire remains under investigation.

The Red Cross is on the scene assisting residents who are afraid they have lost everything.