Evansville, IN — Officials have yet to publicly identify a cause to Wednesday’s deadly home explosion, but outside experts said the blast bears many of the hallmarks found in incidents caused by a natural gas leak.

Such incidents have have killed more than 100 Americans over the past decade and injured hundreds more.

The explosion, which received national attention, killed three people – Charles Hite, 43, Martina Hite, 37, and 29-year-old Jessica Teague – and destroyed four homes in the 1000 block of North Weinbach Avenue in Evansville and damaged at least 39 other homes.

CenterPoint Energy, which supplies electricity and gas to the neighborhood, said crews did not detect the presence of natural gas outside the destroyed homes following the explosion and stated its natural gas system did not appear to be compromised.

“We don’t know if this is gas yet, but it sure has all the footprints of it,” Kuprewicz told the Courier & Press. “The explosions can be of tremendous force.”

If gas is the culprit, Kuprewicz said investigators will have to determine if the leak came from inside the home or from an external gas line.

In internal cases, pipes inside the home leak natural gas into the structure. Kuprewicz said that incorrectly installed appliances or recent renovations are often to blame when an internal leak occurs.In external cases, gas leaks from main lines maintained by the utility provider itself. Natural gas, which is lighter than air, will try to reach the surface when it leaks from an underground pipe, Kuprewicz said. If the gas hits resistance, such as asphalt, it can begin to migrate sideways for upwards of 100 feet, oftentimes finding its upward escape inside a home.

“This is definitely a high-level explosion, as we call it in the industry,” McDonald said.

Based on his experience investigating gas leaks, McDonald said a key component for state fire marshals will be the odorant, or smell, that’s added to methane natural gas — especially in this case, given the fact two people died inside the home that exploded.

Regulations typically require utility companies to inject enough odorant into natural gas for the average person to be able to smell a gas leak at a concentration roughly equivalent to 1% of the air inside a home. Explosions, McDonald said, typically occur at a 5% to 15% concentration.

On Thursday, CenterPoint Energy spokeswoman Natalie Hedde said there was nothing wrong with “CenterPoint’s system” that would have caused the explosion.

“CenterPoint Energy completed several leak surveys in the surrounding areas, with all readings on the outside of the structure reporting back negative, indicating no natural gas leaks detected,” Hedde said through a news release. “Additionally, pressure readings performed on CenterPoint Energy’s natural gas lines were normal.”

Kuprewicz said the lack of natural gas readings outside the home doesn’t mean natural gas didn’t cause the explosion.

CenterPoint’s responsibilities cover the external lines, he said, but state investigators will likely conduct a forensic analysis of pipes within the home to determine if an internal gas leak caused the explosion.

“There are certain protocols that will help rule out the CenterPoint system from being the likely culprit,” Kuprewicz said. “If they were to find an internal piece of pipe that was broken, there are forensic ways to determine whether the failure occurred before the blast or after.”

The investigation could take months, and even then, there’s no guarantee a forensic analysis will determine who was at fault for the explosion.

2017 Evansville home explosion cause ‘undetermined’

Five years ago, a home explosion on Hercules Avenue in Evansville killed two people: Sharon Mand and Kathleen Woolems. The blast also injured three others, including a child.

The Evansville Fire Department closed its months-long investigation without determining a cause, but the survivors and deceased victims’ families alleged in a lawsuit that Vectren Energy, which is now CenterPoint Energy, failed to properly inspect gas lines. A judge sided with the utility provider, finding there was no proof of wrongdoing.