A natural gas leak inside a Caledon home is to blame for a massive explosion that rocked the quiet neighbourhood last week, investigators have determined.

In the early morning hours of Feb. 3, a sudden explosion shook Maple Grove Road and surrounding streets.

The sheer force of the blast completely levelled a home and caused varying damage to several nearby houses.

Fifty-four-year-old Joseph Westcott was later found dead on the property.

For the past four days, investigators with the Ontario Fire Marshal have assessed the scope of the damage and combed through the rubble for evidence of a cause.

Heavy equipment was brought in to lift large pieces of the shattered home. In some cases, crew members sifted through the shrapnel on their hands and knees. A drone was used on several occasions to survey the debris field, which shrunk daily as investigators made progress.

By Wednesday night, the OFM had determined the blast to be a result of a natural gas leak inside the house.

However, it is not clear if the leak was accidental or intentional. Investigator Skye Lormier said it may not ever be determined. No criminal charges have been laid.

Lormier said some piping from the home is still being analyzed and that the Technical Standards and Safety Authority (TSSA) and Enbridge have become involved in the investigation.

The explosion forced dozens of residents out of their homes. By Tuesday, seven of the residences impacted by the blast were deemed safe and those homeowners were allowed to return.

Four other homes were turned over to the Town of Caledon for further structural examination.

The remaining four properties, considered to be the most severely damaged, were under OFM investigation until Wednesday night, when they were released to the town for inspection.

“The process for these properties is similar to other area properties damaged by the explosion. Based on inspections by town building inspectors, orders have been issued that these homes are currently unsafe to occupy,” the Town of Caledon wrote in a news release.

“These homeowners, along with their insurance agencies, will be granted access so that adjusters, engineers and/or other experts can assess any damage.”

Once the home is assessed and determined to be safe, only then can the homeowners regain full access.

The town anticipates that the process could take “months” for these four homes in particular.

In the meantime, a fence will be installed around the homes in question for security.