The National Transportation Safety Board is looking into a weekend house fire in Atlanta that claimed the lives of two people, the organization said on Sunday.

According to a tweet from the NTSB, which looks into pipeline accidents, the fire involved natural gas.

On December 3, about 8:30 a.m., according to a statement from the fire department, workers were dispatched to a home in northwest Atlanta, the Atlanta Journal-Constitution reported. Officials with the Atlanta Fire Rescue Department reported that after the intense fire was put out, a gas leak was discovered in the front yard.

According to additional news sources, Atlanta Gas Light, the biggest natural gas distributor in the Southeast, blamed the fire on the leak. According to fire officials, the causes are still being looked into.