Faulty wiring and flammable ceiling materials are suspected as the major causes of the fire at a hospital in Miryang, South Gyeongsang Province, which has so far claimed 38 lives and left 151 people hurt, investigators reported on Sunday, after a third on-site inspection.

The special probe team, which includes officials from police, fire and forensics departments, focused on the structure of the building and whether the electrical wiring system had been managed properly, suspecting that defective wiring had sparked the deadly fire.

The results of the latest examination are expected to be released before Feb. 10.

The investigators also found that the hospital did not operate an emergency electricity generator, which is seen as the reason for the deaths of the victims who were on ventilators.

They checked the fire prevention measures at the hospital to find how the smoke had spread so quickly to the upper floors of the six-story building. They identified four suspected routes by which it could travel. Most of the victims appear to have died from smoke inhalation, with none dying from burns.

The fire broke out around 7:30 a.m. in the ceiling of a changing room in the emergency room on the first floor of Miryang’s 93-bed Sejong Hospital. The fire was put out at 10:26 a.m. The adjoining 98-bed nursing home was not affected by the fire.

While the fire did not spread to the upper floors, the main building did not have a water sprinkler system to douse the flames early on.

Only buildings with more than 10 floors and public facilities that admit 500 people or more, or have a total floor space larger than 5,000 square meters, are required by law to install sprinklers.

A separate law was revised in 2014 requiring the installation in all elderly care hospitals, but the grace period to allow for installation does not end until June.

The National Forensic Service also pointed to the highly inflammable Styrofoam panels that covered the ceiling of the dressing room as one of the major causes of the high number of casualties, as it would have burned quickly, releasing thick smoke and toxic gas.

The authorities explained that fire developed in a way that is similar to a blaze that killed 29 people at a fitness center in Jecheon, North Chungcheong Province, in late December.

“The structure of the hospital ceiling is similar to the walls of the fitness center in Jecheon, which had the inflammable cladding covering the walls of the building,” an official from the forensic institute said.

According to police, about 18 patients on the second floor were bound to the beds, while two nurses who were in charge of the third and fifth floors testified that roughly another 10 patients had one hand tied to the bed on those two floors.

“It is not exact, but about 18 patients were tied to the bed with taekwondo belts and ropes. It took about 30 seconds to one minute to untie each one of them,” a firefighter said.

Many of the patients admitted to the hospital reportedly suffered from mobility issues and dementia. The hospital appears to have tied up the patients to prevent them falling from the bed and to stop them pulling out their IV treatments.

Fire officials said the death toll could increase, as some of the patients taken to the six nearby hospitals are in a serious condition.

A memorial altar for the victims was set up in the city Saturday as part of efforts to offer a place for citizens to express condolences. The city said over 4,300 citizens paid their respects there, as of Sunday morning.

President Moon Jae-in paid a surprise visit to the site of the accident on Saturday, and called for additional support to prevent further casualties and damages from the incident.

By Jo He-rim (herim@heraldcorp.com)