One week after the deadly Marco Polo fire, investigators still have not determined a cause and have no timeline for when they might figure it out even though they’ve already pinpointed the apartment where the blaze started.

“All I can say is that the investigation is progressing,” Honolulu Fire Capt. David Jenkins said Friday.

A complicating factor in the investigation is the fact that the 26th-floor apartment where the fire began, No. 2602, was completely gutted — to an unrecognizable point, according to one resident who saw the damage up close afterward — as were many other units on that floor.

The rampaging blaze burned for four hours, causing fire, heat or smoke damage to more than 80 units in the 36-floor condominium on Kapiolani Boulevard, Jenkins said. More than 30 apartments are considered a total loss, and an additional 130 units received various levels of water damage.

Three people died on the 26th floor. A dozen more were treated for injuries, with five people transported in serious condition to nearby hospitals. One firefighter was treated and transported to a hospital for heat exhaustion. He has since been released.

Although a damage estimate is still being calculated, Jenkins said the fire is considered to be one of the most destructive in Hono­lulu’s recent history.

Tom Schmidt, a 26th-floor resident and direct neighbor of the suspect apartment, said he was able to walk down his hallway after the fire and peer at the carnage. Many of the front doors were melted away, windows were blown out and lots of the interior walls were gone, he said.

“These units didn’t have any interiors,” Schmidt said. “They were all completely burned down, only soot and ash left. There were no cabinets left at all. The cabinets, gone; the countertops, gone.”

Schmidt, a Marco Polo apartment owner who has lived in the building since it opened in 1971, said he found his belongings largely intact, although they obviously had smoke and water damage.

He ambled down the hallway for about 10 minutes before being shooed away by a fire official. He said he suffered headaches from an intense odor.

A retired Realtor and one of the original agents who sold the Marco Polo units from the beginning, Schmidt was at a Bishop Street appointment when he started receiving phone calls that his building was on fire.

He didn’t panic, he said, because units have burned in the past. But when he approached the building, he ended up parking his car along nearby Lime Street to watch the fire. That’s when dread filled him as he counted the floors to his apartment and realized his apartment was in the direct line of the fire.

Schmidt, who is now living in a hotel and expects to be there for at least six months, said the wind was strong that day.

“The building was built to catch the wind and keep the hallways fresh,” he said.

While that’s normally a good thing, Schmidt said he believes the wind added fuel to the fire, pushing it across the building to compound the damage.

Retired Fire Capt. Richard Soo said he wondered why there was so much destruction from the Marco Polo fire. It’s common for high-rise fires to be confined to a single unit, he said, but in this case the wind could have helped spread the flames.

“When I was trained (in the mid-’70s), I was always hopeful that a fire in a building with no sprinkler system would be resisted by the hallway doors, which are supposed to have a one-hour rating,” he said. “But if a door is left ajar …”

The high degree of devastation likely prompted fire inspectors to turn for help from agencies such as the federal Bureau of Alcohol, Tobacco, Firearms and Explosives, Soo said. The ATF, as the agency is called, has greater access to labs to test materials.

The interior walls are often key to pinpointing the precise origin, Soo said, but that may be impossible in this case with everything charred away by intense heat.

Fire officials so far have given no indication they suspect any criminal wrongdoing in connection with the fire.

Soo said the department will conduct its investigation, and if any suspicious evidence is found, it will be turned over to the Honolulu Police Department for criminal prosecution.