KARNES COUNTY, Texas – Firefighters are monitoring a potentially dangerous situation after battling a large fire at a drilling fluids facility in Kenedy, Texas, on Sunday.

The fire is now under control, but crews kept an eye out all night to ensure the safety of the surrounding area.

Crews were called around 5 p.m. Sunday evening after an old Walmart building went up in flames. The building is now used by an oil company called Newpark to store fracking fluids.

Ten different fire departments are monitoring the scene.

Kenedy Police Chief Duane DuBose said the fire intensified because of combustible powders and liquids being stored in the building.

Residents at a nearby apartment complex and RV park were forced to evacuate.

On Monday afternoon, the shelter for those evacauted was relocated to Kenedy Middle School's George w. Dumont Gym, which is at 401. FM 719 in Kenedy. Free meals were being provided. 

"It was just a big old explosion. Looks like a volcano erupted to be honest. All I saw was black smoke everywhere... fire... flames,” said witness Amberosia Aleman.

Kenedy City Hall opened as a temporary shelter for the evacuees.

DuBose said Bexar County's Emergency Management team was called in to determine if the chemicals are harmful. As of now, they don't believe there's a threat to people living in that immediate area.

So far there is no word on what started the fire.

WATCH: Check out this video shot by @amberosia23 out of Kenedy. This video taken right after a massive explosion occurred at an old Walmart building in town. @SpecNewsSA @SpecNewsATX pic.twitter.com/aBkSMB1dzb