A diverted American Airlines plane caught fire on the tarmac after making an emergency landing at Denver International Airport with engine issues Thursday evening, forcing passengers to evacuate the burning aircraft, authorities said.

Twelve people were transported to hospitals with minor injuries after evacuating the Boeing 737-800, airport spokesperson Michael Konopasek said.

The fire broke out about 6 p.m. when the aircraft was at Gate C38, Konopasek said Friday morning. “Operations remain normal overall,” he said. “The fire only affected Gate C38. We plan on having that gate up and running later today.”

The National Transportation Safety Board launched an investigation of what happened when the American Airlines Flight 1006 departed from Colorado Springs for Dallas Fort Worth International Airport and was diverted to DIA. The aircraft made an emergency landing in Denver because of engine concerns. After landing, the plane sustained a fire, and passengers and crew members were evacuated, the NTSB said Friday.

Two NTSB investigators with expertise in commercial aircraft and power plants were expected to arrive at DIA to conduct interviews with crew members and witnesses, to examine the aircraft, which was taken to a hangar, and to obtain “other data that could contain information relevant to the investigation,” the NTSB said.

The plane had departed from Colorado Springs when crew members reported “engine vibrations,” according to a statement from the Federal Aviation Administration. The crew members told air traffic controllers shortly before landing in Denver that the plane was experiencing “high engine vibrations” and was “cruising slower than normal” in a recording published on LiveATC.net.

Tracking data from Flight Aware shows the 737 left Colorado Springs at 4:52 p.m., diverted at 5:14 p.m. and landed in Denver at 5:55 p.m.

The plane landed safely and was taxiing when it experienced “an engine-related issue,” American Airlines spokesperson Brian Metham said in a statement.

After the fire started at the gate about 6 p.m., passengers were evacuated with slides, and the fire was extinguished, he said.There were 172 passengers and six crew members on board, he said. A replacement American Airlines aircraft transported affected passengers to Dallas on Friday morning, airline spokesperson Gianna Urgo said.

For Colorado Springs resident Ingrid Hibbitts and her family, the flight was the first leg of an international trip to Argentina for a wedding.

Hibbitts said passengers became nervous when the flight crew announced the plane was rerouting to Denver because of engine problems. After what she described as an abrupt and bumpy landing at DIA, some spotted smoke and began to scream.

“I looked out of the window, and I saw flames from the window, and I saw the window start bubbling,” she said. “I was thinking, ‘Oh, my God, I hope the plane doesn’t blow up.’”

The group — which Hibbitts said included older adults and families with young children — scrambled to evacuate onto the plane’s wings and down emergency slides. Hibbitts was seated apart from her husband and two daughters, and she reunited with them on the tarmac.

“It was kind of like a nightmare,” she said.

Once on the ground, she witnessed passengers being treated for smoke inhalation and other medical problems. As of Friday morning, her family had caught a plane to Dallas and were preparing to board another American Airlines flight to Miami.

“Honestly, I’m a little nervous. I’m telling myself to think logically,” Hibbitts said. “Nothing like this should happen. Someone should be looking out for the safety of all passengers at all times.”

On Friday afternoon, flight-tracking software showed eight American Flights were canceled and one was delayed.

News of the fire spread quickly on social media after passengers posted videos of smoke billowing from the plane and passengers evacuating onto the wings.

“We thank our crew members, DEN team and first responders for their quick and decisive action with the safety of everyone on board and on the ground as the priority,” American Airlines said in a statement.

As the FAA and NTSB investigate, a preliminary report will be available within 30 days, according to the agency. The probable cause of the fire, and contributing factors, will be presented in a final report expected within one or two years.

The country has seen a recent spate of aviation disasters and close calls stoking fears about air travel, although flying remains a very safe mode of transport.

Recent on-the-ground incidents have included a plane that crashed and flipped over upon landing in Toronto and a Japan Airlines plane that clipped a parked Delta plane while it was taxiing at the Seattle airport.

After hearing midflight that something was wrong with the engine and the plane would have to land, passenger Daniel Friedman said in an interview with a WRAL-TV reporter at DIA that he started thinking about who he would call and in what order and writing a eulogy.

“Really I just wanted to make sure we got here safe and didn’t know if it was going to happen or not,” Friendman said.

The Associated Press contributed to this report.