The Smith County Fire Marshal's Office has determined the preliminary cause of an explosive fire at a welding company was accidental, though fire investigators have yet to assess the point of origin because the property is still smoldering.

Assistant Fire Marshal Chad Hague said the determination is based on what they can see at the site, in the 3500 block of U.S. Highway 271.

Fire Marshal Connie McCoy-Wasson and her staff were at Tyler Welders Supply on Thursday morning, joined by an official with the state fire marshal's office, waiting to get the go-ahead to begin the investigation into the cause of a fire that caused multiple explosions at an acetylene storage area in the rear of the business on Tuesday afternoon.

Safety officials from Tyler Welders Supply and Praxair, an industrial gas distributor, conducted air quality tests and looked at the site this morning but small flames were still present in the pile of exploded acetylene gas canisters,making it unsafe for inspectors to conduct their work, McCoy-Wasson said.

McCoy Wasson was not sure if it would be safe for the inspection to begin due to the metal being hot and the gases still continuing to burn off.

The Smith County Fire Marshal's Office will be assisted by the State Fire Marshal's Office District 1.

Occupational Safety and Health Administration spokesman Juan Rodriguez said OSHA will not investigate the fire because it investigates only when there is a catastrophe with a fatality or three or more people are injured in an incident.

According to OSHA's Integrated Management Information System, no OSHA inspections have been done on Tyler Welders Group or other supply stores owned by Ronnie and Melvin Ruyle - Tyler Welders Supply, United Welding Specialties in Longview, Henderson Welding Supply, Paris Obygen Company, The Welding Store in Sulphur Springs or Arc-La-Tec Welding Supply in Shreveport, Louisiana.