Los Angeles International Airport evacuated a terminal on Monday after a possible carbon dioxide leak sickened at least four people, including one person listed in "grave condition," officials said.
Terminal 8, utilized by United Airlines, was temporarily cleared of all passengers around 8 a.m. local time as firefighters investigated the apparent leak, the airport said.
Three people were in mild distress and one in "grave condition" due to the leak, the Los Angeles Fire Department said.
Fire officials said during a news briefing that the leak came from a fire suppression system inside an electrical room. The system discharges carbon dioxide instead of water so that electrical equipment isn't damaged.
The four people affected by the leak were independent contractors inside the room, fire officials said.
Since carbon dioxide is heavier than oxygen, the deluge of carbon dioxide gas displaced the air in the room. A male worker in his 50s who was inside the room had the oxygen in his blood displaced by the carbon dioxide and went into cardiac arrest, the LAFD said.
After about two hours, the airport announced that firefighters deemed the building safe and would reopen Terminal 8.
No updates on the conditions of those affected by the apparent gas leak were immediately available.
Passengers were initially evacuated from Terminal 8 and brought to Terminal 7 for screening when the apparent gas leak first occurred, the airport said.
United flights arriving at the airport were being held at their origin airport as firefighters investigated the unspecified leak, according to airport officials. The airport advised all passengers to contact their airline for specific flight information.
Terminal 8 and United Airlines was the only facility impacted by the hazmat investigation, the airline said.
While officials have not stated where the gas leaked from, local reports say it appears to have taken place during construction work and affected construction workers.
This is a breaking news story; check back for updates.