Investigators are still searching for what caused a Fitchburg home to explode last month.

Thursday marks three weeks since the explosion that rocked the neighborhood.

Debris once filled the streets and yards of homes around the area, but the restoration process for residents is just beginning.

"They are in the emergency phase, then they go into the cleanup phase and then they go into the house to tear things apart and then you have to put it back together," resident Mary Katic said.

Luckily, Katic and her family weren't home at the time when their neighbor's house exploded, but now they are left dealing with the aftermath.

Katic has three weeks to remove all of her belongings from the house she and her husband have lived in for the past 26 years. That's when contractors will start a remediation plan.

Restoration companies, like Paul Davis are set to start work on some homes this week. Contractors have not been able to start work on most of the homes in the area, as they spent additional time to assess the extent of the damage.

"There aren't that many explosions so you don't have that much experience with them, and they are often all different. It's just determining where the damage starts and where the damage stops to make sure that everything that was affected by the explosion is addressed," said Jim Hirsh, president of Paul Davis restoration.

At least two homes near the explosion are a complete loss. Damage to 20 other homes is still being assessed.

In the search for answers, Fitchburg Fire Chief Joe Pulvermacher said there is a long list of potential causes.

"The responsible thing to do with an investigation is to start with the knowns and work toward the unknowns, and I think that's where we are at right now," Pulvermacher said.