Fire investigators don’t know what sparked the blaze that destroyed the Guadalajara Fiesta Grill, but there is no indication it was deliberately set, a fire official said.

On Thursday the Tucson Fire Department released its findings on the July 26 fire that destroyed the eastside eatery.

Though investigators are classifying the fire as undetermined, they were able to pinpoint where it started, in the southeast corner of the restaurant.

“The classification of undetermined is assigned when the cause cannot be proven to an acceptable level of certainty,” Capt. Barrett Baker, spokesman for the Tucson Fire Department, said in a news release. “Based on witness statements, fire patterns, fire dynamics and other data collected by the investigators from the fire scene this determination is the only acceptable classification at this time.”

That classification can change in the future if new information is discovered, Baker said.

Someone who saw smoke coming from the restaurant called in the fire, at 750 N. Kolb Road between East Speedway and Broadway, to 911 at 4:45 a.m.

Firefighters arrived within minutes to find the restaurant’s attic engulfed in fire, with heavy smoke and flames coming from the roof.

The majority of the flames were extinguished within an hour, but crews continued to pour water on the building for several more hours to extinguish hot spots.

The restaurant sustained “heavy, heavy fire damage,” Baker said at the time, and the building is a total loss.

The restaurant’s insurance company estimated the total value of the property and the building at $1.8 million, he said.

A former north side affiliate of Guadalajara Fiesta Grill is still closed for repairs after a fire in a storage room May 29.

Guadalajara Original Grill, 1220 E. Prince Road and North Mountain Avenue, suffered minimal damage when a fire started in a storage closet, but smoke caused heavy damage throughout the building.

The cause of that fire was classified as undetermined as well, said TFD Capt. Chris Jurvig, a TFD spokesman, who estimated the damage at the time of the fire at $200,000.

An Aug. 11 post on the Guadalajara Original Grill Facebook page stated that the restaurant is expected to reopen the first week of October. In the meantime, the operators will set up a tent with a limited menu at the Aug. 29 University of Arizona tailgate party prior to the football game.