LACKAWANNA, N.Y. — Authorities have completed their investigation into a deadly house explosion in Lackawanna.

The mayor released a statement Monday, saying the explosion was determined to be caused by a natural gas leak in the basement of the home.

It is unknown what ignited the explosion at this time.

National Fuel says it’s testing of the service lines on Bedford Avenue found no evidence of a gas leak and also emphasized its cooperated with investigators and extended its condolences to the victim’s family.. They released a statement that said, in part:

“National Fuel is responsible for the maintenance and operation of the main lines and the service lines up to the house’s meter. The house lines and connections to natural gas equipment and appliances within the home are the responsibility of each customer, therefore we are unable to comment on the customers piping or equipment.”

First responders responded to Bedford Avenue last month.

Irene Sanok, 92, was pronounced dead at the scene.

The house was destroyed. Seven other homes were damaged in the blast.

The mayor says an emergency demolition order has been issued for one of those homes.