United Airlines said Friday that it was working with health officials to contact passengers who might have been exposed to the coronavirus by a male passenger who died after a medical emergency on a recent flight.

The four flight attendants who responded to the emergency on board the flight, United 591, also went into quarantine for 14 days after the plane landed at its destination in Los Angeles, the flight attendants’ union said.

The flight, which took off from Orlando, Florida, and was diverted to New Orleans, prompted widespread alarm on social media after reports indicated that the man’s wife had told emergency medical workers that he had tested positive for the virus.

United Airlines said Friday that the man’s wife was overheard telling an emergency medical worker that her husband had symptoms of COVID-19, including loss of taste and smell.

But United officials said medical professionals did not confirm at the time that the man had tested positive for the virus, and they are still not sure if he was infected. When the flight was diverted to New Orleans, the airline said, it was told that the passenger had experienced cardiac arrest.

Nevertheless, United Airlines said it had been contacted by the Centers for Disease Control and Prevention. “We are sharing requested information with the agency so they can work with local health officials to conduct outreach to any customer the CDC believes may be at risk for possible exposure or infection,” the airline said.

The CDC said Friday that it was in the process of collecting information.

Taylor Garland, a spokesperson for the union that represents flight attendants at 17 airlines, including United, said that after the plane landed in Los Angeles, the crew of four flight attendants was “quarantined for 14 days per written guidelines.”

United said that when the passenger had checked in for the flight, he had attested, as part of a “Ready-to-Fly” checklist, that he had not tested positive for the coronavirus and did not have symptoms of COVID-19. But the passenger may not have been truthful, the airline indicated.

The man’s family later confirmed that he had been “feeling sick leading up to the day of travel,” United said. The man also had preexisting conditions, including high blood pressure and upper respiratory issues, the airline said.

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