TULSA, Oklahoma - Investigators still don't know what caused an explosion that forced more than a dozen families from their apartments near 45th and Garnett Wednesday night.

The 16 families who lived in the Bristol Park Apartment building spent the day in the front office getting help from the Red Cross.

The families said they felt fortunate no one was seriously hurt. Most are staying at hotels or with family.

Plastic and wood cover most of the large hole in the middle of the Bristol Park Apartment building.

Wednesday fire trucks and fire fighters surrounded the building after the sound of an explosion alarmed everyone nearby, including neighbors Shanee Richard and Joyce Hargrove.

“He was in bed asleep and as soon after he heard the noise, he came running and he didn't know what it was and we didn't either and it shook him," Richard said.

Hargrove said, "It was pretty forceful, for the rumble and the way it sounded."

Hargrove walked out on her balcony to see what was going on.

Even though it was dark, from her third story apartment, she could see the chaos happening next door.

"I saw people running around and the next thing I knew I saw fire trucks coming," Hargrove said.

Fortunately, the families inside the 16 apartments had already run outside and escaped the small fire.

"It kind of glowed a little bit. There was smoke coming out of it," Hargrove said.

Tulsa Fire Department officials said the initial call was about a gas odor. While on the way, it escalated to an explosion and more fire trucks were brought in.as smoke filled the air.

"It was kind of weird, it was something you just weren't expecting," Hargrove said.

Now fire investigators are trying to figure out what caused it.

TFD said they ruled out a meth lab and think it was possibly a natural gas leak, but don't know for sure.

Four of the apartments were destroyed, the rest are damaged, but some of the families were allowed to go in and quickly grab what they could.

The Red Cross is helping 12 of the families who lived at the complex with a temporary place to stay.