Dozens of passengers were forced to stand on the wing of an American Airlines plane at Denver International Airport as they evacuated the aircraft after one of its engines caught fire Thursday evening, CNN reports.

American Airlines Flight 1006, a Boeing 737-800 en route to Dallas-Fort Worth from Colorado Springs with 172 passengers and six crew aboard, diverted to Denver around 5:15 p.m. local time, after the crew reported “engine vibrations,” CNN quoted the U.S. Federal Aviation Administration (FAA) as saying.

“After landing and while taxiing to the gate an engine caught fire,” the FAA said.

The FAA is investigating.

The fire was extinguished and all passengers were evacuated, a Denver International Airport spokesperson told CNN.

Twelve passengers were taken to the hospital with minor injuries, the Denver Fire Department told CNN.