More than a week after an empty mansion exploded in Gladwyne, rocking an otherwise quiet Sunday night along the Main Line, authorities have yet to officially determine what caused the blast.

On Friday, investigators finished their work at the property on the 600 block of Dodds Lane and released it to the owners, said Thomas Walsh, spokesman for Lower Merion Township. But crews left the property with few answers.

Officials have sent items from the scene to a lab, and analysis could take several weeks, Walsh said. At that time, authorities should know what caused the explosion and whether the blast was an accident or the result of suspicious activity.

Debris in in the trees around the leveled home in Gladwyne.
Tom Gralish
Debris in in the trees around the leveled home in Gladwyne.

The 9,000-square foot home belonged to a limited partnership, GF 2014, owned by area developer Michael Grasso. His brother Joseph Grasso, 57, a developer and investor, and sister-in-law Donna Grasso, 52, sold the property to him in 2016 for nearly $4 million. Members of the family have not responded to multiple requests for comment about the explosion.

No one was injured in the Nov. 4 blast. The home had been undergoing renovations for years and was unoccupied. Surrounding homes suffered minor damage.

Utility and emergency workers gather at the scene a day after a gas explosion leveled an empty mansion in Gladwyne,
DAVID MAIALETTI / Staff Photographer
Utility and emergency workers gather at the scene a day after a gas explosion leveled an empty mansion in Gladwyne,

Lower Merion fire and police officials have been assisted in the investigation by the Bureau of Alcohol, Tobacco, Firearms, and Explosives and the Pennsylvania State Police fire marshal unit.

Authorities quickly determined that the incident was isolated and posed was no threat to the neighborhood.

Peco officials said gas explosions are rare, but if homeowners smell gas, they should immediately leave the house and call their service provider.