EVANSVILLE, Ind. - A yet-unsourced home explosion in an Indiana town killed three people and damaged at least 39 other homes Wednesday afternoon, according to local fire departments. 

It's unknown what caused the explosion, according to the Evansville mayor.

Initial surveys showed 39 homes were severely to minorly damaged, and according to the American Red Cross, 11 of those homes were left completely uninhabitable. 

Search and rescue has been delayed until the Bureau of Alcohol, Tobacco, Firearms, and Explosives can secure each home and confirm there is no threat of further explosions. 

Authorities also asked residents to stay clear of the area.