HOUSTON -

One minute, everything was normal for the family living in a northeast Houston apartment; the next, their home was on fire.

Firefighters say the cause was gas filling the air, without their knowledge. That all changed when someone lit a cigarette.

An entire family was taken to the hospital after a flash fire inside their apartment.  Fire investigators say a mom, dad and two children are being treated for minor injuries and are expected to be OK.  Still, it was a scary morning for people who live in the apartment building.

From the outside of the house on Laredo, you can't see any damage.  It's inside where the flash fire occurred.

The building is divided into four apartments and it's under renovation.

"He lit a cigarette and it just went up. He came out and was touching his face. It was burnt," said resident Sharyn Flores.

She was home when the fire started.

"It was actually two small children and two adults that got burned. It was bad.  Really, really, bad," Flores said.

"When I came outside the little boy ran to me. He was on fire from head to toe and I had to put him out," said Ashley Grubbs.

Neighbors say the little boy's sister, who's about 3 year's old,  escaped the fire then ran back inside because she got scared. Flores went in to help and says she found her hiding in her bed.

"It took me forever to get her outside. She didn't want to come outside the house," said Flores.

People who live here think a gas leak caused the fire. They say work was being done on the line so they could connect the stove.

A CenterPoint Energy spokesperson told Local 2 that the problem was on the customer's end, but they did send a crew to come out and investigate. While in the neighborhood, they found a small link one street over and spent several hours repairing it.

CenterPoint crews have left the neighborhood.  A spokesperson tells us that leak had nothing to do with the fire.

Firefighters put the fire out in about 10 minutes.  The building reportedly has fire and smoke damage. People who live there tell Local 2 they did lose some belongings in the fire.