Another passenger said the cabin filled with smoke as the plane landed.
“The oxygen masks never came down and people began to freak out,” D.J. Semenza told CNN. “The crew tried to keep calm and eventually called for an evacuation.”
Delta passengers mill around their plane after being evacuated in Denver.
The smoke was detected prior to the plane reaching the gate, said Denver International Airport spokeswoman Emily Williams. Passengers were bused to the terminal.
“The safety of Delta’s customers and crew is our top priority and we apologize for the concern this situation has caused,” Delta said Wednesday in a statement.
Delta blamed the smoke on a small amount of hydraulic fluid dripping onto the aircraft’s auxiliary power unit — a small jet engine located in the rear of the plane. The APU is usually activated while aircraft are on the ground as a way to generate electricity.
When the fluid made contact with the hot APU, it created smoke, which was blown into the cabin, the airline said.