The remains of Hi Point Urology

Bellefontaine Fire Chief J.P. Schulz said it appears that a propane leak was ignited by mechanical appliances in the basement.

Schulz, who's been a firefighter for twenty years, says the Wednesday night blast was the strongest explosion he's ever seen.

Residents in Belle Center, Huntsville, and West Mansfield heard or felt the blast.

Debris was found up to half a mile from the scene.

The explosion completely destroyed the building, which was used by Dr. Matthew Hasford the last several years.

Hasford closed the practice in March.

Chief Schulz says the exact cause remains undetermined and the investigation will continue.

The State Fire Marshal's Office and the Federal Bureau of Alcohol, Tobacco, and Firearms assisted local authorities last Thursday.