Three people have died and at least 39 homes were damaged after an explosion in Evansville, Indiana.

"There could be other victims, we have not completed our search," Connelly said. "The buildings are not yet safe to enter."

The initial survey shows that 39 houses have suffered "severe to minor damage," the chief added.

The chief later told reporters that 11 of those 39 homes were left inhabitable, adding that the American Red Cross will be helping those affected families.

Evansville is about 3 hours southwest of Indianapolis.

The mayor told CNN affiliate WFIE that the scene was "devastating" and that it will likely take a while to figure out what happened.

A structural collapse team was called in to survey buildings and to make sure that all gas and electric circuits "had integrity," the chief said.

At least eight agencies were on the scene, including the Bureau of Alcohol, Tobacco, Firearms and Explosives and the State Fire Marshal.