HONOLULU (KHON2) — First responders leaders gathered at Honolulu Hale to provide an update on the investigation of the heartbreaking ambulance fire that left one patient dead and a paramedic fighting for his life.

The meeting was held at Honolulu Hale on Wednesday.

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Scheduled to speak were the Director of the Honolulu Department of Emergency Services Dr. Jim Ireland, Honolulu Fire Chief Sheldon “Kalani” Hao, Honolulu Police Chief Arthur “Joe” Logan, and Honolulu Mayor Rick Blangiardi.

Investigators have narrowed down the possible cause of the Emergency Medical Services ambulance fire that killed a patient. But why it went up in flames is still unknown. EMS said there was a loud pop when the patient’s breathing device was connected to a portable oxygen tank. And that’s when the flames erupted.

The fire occurred last month as the ambulance was transporting 91-year-old Fred Kaneshiro to Adventist Health Castle Hospital. Investigators said Kaneshiro was wearing a continuous positive airway pressure to help him breathe which is connected to a large oxygen tank connected to the wall of the ambulance.

Emergency Services Director Dr. James Ireland said the paramedic disconnected the CPAP in order to connect it to a smaller portable oxygen tank as they approached the hospital.

“There was a sound described as a pop followed by a bright flash of light with the back of the ambulance immediately filling with smoke and fire,” said Ireland.

Ireland said the investigation is now focused on the portable oxygen tank and the regulator. How either of these devices ignited is still unknown. Investigators were able to talk to paramedic Jeff Wilkinson who is still recovering in the hospital and the EMT who was driving the ambulance.

He added that EMS crews use the CPAP and oxygen regularly. And there’s no indication that anyone did anything wrong.

Ireland pointed out that these findings are still preliminary so at this point, EMS is not making any major changes to safety protocols.

“We don’t have a final result and an actual cause of the incident within the regulator oxygen tank mechanism. I don’t want to jump the gun but I think reviewing just the safe oxygen policies is what we’re doing now,” Ireland said.

Ireland also stated that crews inspect the equipment in the ambulance daily and a separate company that supplies the oxygen inspects the tanks. He added that the three ambulances that have been put out of service will stay out of service.

As for Wilkinson, Ireland said he was able to visit the paramedic who is now out of intensive care.

“It was an emotional meeting for me. I’m just so happy that he’s improving, he’s so grateful. We had calls and well wishes from around the country. I think even a few outside of our country,” Ireland said.

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Officials are continuing to investigate the incident.