Originally Published: 10 AUG 22 17:18 ET

Updated: 11 AUG 22 10:05 ET

By Claudia Dominguez and Michelle Watson, CNN

(CNN) -- Authorities have yet to determine the cause of a house explosion Wednesday that left three people dead and damaged at least 39 homes in Evansville, Indiana, the city's fire chief said.

The investigation is ongoing, Chief Mike Connelly said in a news conference Thursday morning, adding it will be a "tedious process."

More than a dozen agencies responded to the scene, which Mayor Lloyd Winnecke previously described to CNN affiliate WFIE as "devastating," saying it would likely take time to figure out what happened.

In addition to the three people killed, at least one person was transported to the hospital for non-life-threatening injuries.

There could be other victims, Connelly told reporters Wednesday evening. At that time, authorities had yet to complete their search because buildings were still not safe to enter.

An initial survey showed 39 houses suffered "severe to minor damage," the chief added. Eleven homes were left uninhabitable, he said, adding the American Red Cross will help affected families. Evansville, home to about 116,000 people, is about a three-hours' drive southwest of Indianapolis.

Destroyed and damaged homes and piles of debris featured in photos posted on Twitter by the mayor, who said first responders and local departments will "keep residents in the Willemette Village/Wesselman Park neighborhoods safe and informed."

"I'd seen photos that have been placed online, but once I walked up to the residence itself and saw the devastation with my own eyes, it was, I mean, it was a gut punch," Winnecke said Wednesday.

"Across the street from the explosion you'll see house after house that has windows blown out, that has you know there's insulation blown out from homes," the mayor added.

A structural collapse team was called in to survey buildings and to make sure all gas and electric circuits "had integrity," the chief said Wednesday. At least eight agencies responded, including the Bureau of Alcohol, Tobacco, Firearms and Explosives and the State Fire Marshal.

"They will resume the investigation in the morning," the chief said Wednesday evening. "This is a standard operating procedure for an incident of this magnitude and of this type."

Search and rescue teams will be allowed back into the area once utilities are secured and the ATF determines its part of the investigation is over, Connelly said.

Authorities asked residents to stay away from the area.