HONOLULU (AP)Honolulu investigators can’t determine the cause of a deadly high-rise apartment building fire that resulted in more than $107 million in damage, fire officials said.

“The HFD fire investigators have completed an extensive and scientifically based investigation in full collaboration with other agencies and have classified the fire cause as undetermined,” Fire Chief Manuel Neves said at a news conference Monday.

READ MORE: Better To Give Than Receive, Cowboys CeeDee Lamb Helping Those In Need

“Fire investigators have determined the fire began in the living room of unit 2602. However, due to extensive damage, the exact location and manner in which the fire began could not be ascertained,” he said.

Neves said investigators have been able to rule out some causes of the fire. There was no indication the fire was intentionally set, there’s no evidence of ignitable liquids, and cooking wasn’t to blame, he said.

There was no evidence that there was a drug lab in the apartment, and no drug paraphernalia was found, Neves added.

Investigators have not been able to rule out items found in the living room as an accidental cause of the fire: a compressed gas cylinder, a wand-type lighter, a possible butane cylinder, an air conditioning unit, desk computer, several electrical outlets, and several electrical devices, possibly a laptop computer and a home router, he said.

They also couldn’t rule out smoking-related activities as an accidental cause, Neves said.

Investigators could always reopen the probe if any new information comes to light, he said.

Honolulu Mayor Kirk Caldwell praised the city’s firefighters for their response for the blaze at the 36-story condo shaped like a wave. “I believe because they did their jobs, lives were spared,” he said.

READ MORE: A Closer Look At A Potential Beto O'Rourke Run For Texas Governor

More than 130 firefighters responded to the blaze, ushering people out of the burning building and helping rescue at least six people who were trapped.

“Firefighters climbed over 30 floors, carrying over 80 pounds of equipment on their backs, rushing in to hallways that were like blowtorches, going into smoke-filled rooms. They were our heroes,” he said.

Three people died in the July 14 fire, and another person died weeks later from complications, Neves said. Fire damage was estimated at more than $107 million, and 30 units were totally destroyed. Another 50 units had fire, heat or smoke damage. An additional 130 units received some level of water damage.

The Marco Polo apartment building has no fire sprinkler system. The tower overlooking Waikiki was constructed in 1971, before sprinklers were required for new construction in the city.

An Associated Press investigation after the blaze revealed that the building also failed to update its fire alarms to meet safety standards despite an engineering firm recommending changes several years ago. The tower was not required, however, to meet the standards because they were not part of fire code at the time of original construction.

Caldwell introduced a bill after the fire that would require sprinklers in all high-rise buildings regardless of when they were constructed. Caldwell’s bill would require all buildings taller than 75 feet to install sprinkler systems.

But some Honolulu residents and building associations pushed back, saying requiring retrofitted sprinkler systems would be too costly.

The Honolulu City Council postponed action on the bill about a month after the blaze because they wanted more information from the Honolulu Fire Department, including what caused the fire and how many of the city’s apartment complexes have similar situations.

MORE NEWS: Mask Up, Have Fun At Friday's State Fair Of Texas Opening

(© Copyright 2017 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.)