Residents in southern Indianapolis experienced an explosion on Saturday, Nov. 10, that killed two and damaged dozens of homes, but many are left questioning the cause of the explosion, according to officials.

With no clue to an advanced problem or some type of gas leak to be its cause, the explosion was so powerful that it damaged homes blocks away from its epicenter, according to The Associated Press. Door and windows were found a block or two away from the blast and hundreds of residents were forced to evacuate their Richmond Hill homes. The blast also tore down some homes entirely from their foundations, with the noise of the impact waking up residents three miles away, the report added.

Investigators have yet to determine the cause of the explosion that occurred a hour before midnight on Saturday. So far the only possibilities they have ruled out have been a bomb or a meth lab explosion.

Whole blocks remain uninhabitable and a fire that resulted from the explosion burnt for hours and destroyed dozens of houses before it was put out, according to Yahoo. Around 200 people from the affected neighborhood were sent to a nearby school until they could find someplace to stay.

Officials have not released the identities of the two people killed but a candlelight vigil was held Sunday night at Southwest Elementary School in Greenwood for Jennifer Longworth, according to the report. Longworth is a second-grade teacher and lived with her husband ln one of the homes destroyed by the explosion.

Deputy Code Enforcement Director Adam Collins said as many as 31 homes had such extensive damages that they might have to be demolished. He added that the explosion damaged a total of 80 homes, with an estimated cost of $3.6 million in total damages.

The Bureau of Alcohol, Tobacco, Firearms and Explosives has been asked to help in the investigation, according to ABC News.