A release of carbon dioxide, likely triggered as a firefighting response, nearly killed a man and led to a partial evacuation of Los Angeles International Airport on Monday, authorities said.
Los Angeles fire crews were sent to the airport, one of the country's busiest hubs, shortly after 7 a.m. PT to investigate "the cause of an apparent gas leak in Terminal 8," LAX said in a statement.
Evacuated passengers were sent to Terminal 7, where United Airlines operates at LAX, officials said. A ground stop temporarily kept United Airlines flights from landing at the airport, its major national hub, just south of downtown.
Independent contractors working at LAX, three men and a woman, were sickened by their exposure to fumes coming from a utility closet, firefighters said.
The woman and two of her male colleagues were "treated at scene for minor complaints," the fire department said.
The fourth victim, a man in his 50s, "was found pulseless and non-breathing inside the utility room," the statement said.
Paramedics performed CPR, and his "condition was updated from grave to critical on hospital arrival," firefighters said.
The carbon dioxide exposure was so strong that it was likely a release used in a fire suppression system, Fire Capt. Erik Scott said.
In some systems, carbon dioxide is used instead of water because it can quickly snuff out flames by replacing oxygen, one of the three primary elements of fire, Scott said.
The displacement of oxygen is key to ending fire, but it could also prove deadly to anyone nearby.
"They heard a popping sound, and that was a complete deluge of that system," Scott told reporters. "It doesn't come out as a short sporadic amount of carbon dioxide but rather a full deluge. Obviously that displaces all of the oxygen inside, and three people quickly got out.
"But one adult male approximately 50 years old was still inside. The carbon dioxide displaces the oxygen in the individual's bloodstream, and they went into cardiac arrest," Scott said.
"Firefighters were on scene within five minutes, but we also want to applaud our partners at LAX airport police who jumped in and started CPR right away."
The utility room where the carbon dioxide was released is about 200 feet from the baggage claim area, but no passengers were exposed.
It was not immediately known why the fire-suppression system was triggered.
“They might have been using welding equipment. There might be heat involved or a spark — that’s all part of the active, ongoing investigation," Scott said. "There’s no indication there was any explosion, and there was no fire.”
The use of carbon dioxide as a firefighting agent is rare outside specialized situations.
"It's a unique fire-suppression system that is not used in an average area," Scott said. "But it's used more frequently in an area where there's a high level of electrical components that would be damaged from water."