Bremnen, GA – Investigators are trying to determine whether natural gas or liquid propane caused a deadly hotel fire and explosion in west Georgia, authorities said Thursday.

“We can tell you with certainty that it was a gas explosion,” state Insurance and Safety Fire Commissioner John Oxendine said. “We cannot say which one it was at this point.”

Bremen Fire Chief Clark Farr said natural gas was still being supplied to the property at the time of Tuesday’s blast, and that a liquid propane tank was hooked up and running into the Great Western Inn. The propane was a backup source of energy and authorities are still trying to determine how long it had been active and what it was being used for, Farr said.

Oxendine said the motel, or parts of it, were being switched over to propane because of “billing issues, problems of payment” with the natural gas.

He said in addition to determining the source of the explosion, investigators were trying to find out what set it off.

Human remains found on the first floor of the maintenance and laundry building connected to the extended stay hotel are still being examined at the Georgia Bureau of Investigation Crime Lab for identification and to determine a cause of death.

A 44-year-old maintenance worker, Reese Helton, was missing and feared trapped in the collapsed corner of the building, at the time of the blast. Two other men who had been unaccounted for after a deadly hotel fire and explosion had turned up safe by Wednesday.

The blast rattled the 73-room motel shortly before 9 a.m. Tuesday, investigators said, collapsing the roof over a corner of rooms and dumping debris on cars parked below.

Six to eight rooms were destroyed, with the damage centered on a laundry-maintenance room, said Bremen Fire Chief Clark Farr.