The Transportation Department says it is investigating Delta's actions during a long tarmac delay in extreme Las Vegas heat on Monday.
The incident took place on Delta's Flight 555 to Atlanta, which was eventually canceled. Passenger Krista Garvin, a Fox News field producer, tweeted from the aircraft that the plane sat for nearly three hours on a Harry Reid Airport runway while outdoor temperatures were 111 degrees. The plane returned to the gate after people began to pass out, she wrote.
"Paramedics are on now. I've seen a total of three people wheeled out so far. Oxygen tanks are being pulled out," wrote Garvin. "They said to press your call button if you need medical assistance."
In a statement, Delta said, "We are aware of the DOT's investigation into what took place on DL555 on July 17, and we are working in full cooperation with them."
Delta also apologized for what customers endured. "Delta teams are looking into the circumstances that led to uncomfortable temperatures inside the cabin, and we appreciate the efforts of our people and first responders at Harry Reid International," the airline said.
Transportation Department secretary Pete Buttigieg sounded off about the incident in an interview with Reuters.
"The reports are shocking and we are investigating," he said. "I want to know how it was possible for passengers to be left in triple-digit heat onboard an aircraft for that long. Even at normal temperatures a tarmac delay is not supposed to go that long and we have rules about that, which we are actively enforcing right now."
Under DOT regulations, domestic flights must begin returning to the gate before a tarmac delay reaches three hours in length. Airlines are also required to maintain comfortable cabin temperatures during tarmac delays.