During an emergency landing on Saturday, debris from a United Airlines plane fell on the Denver suburbs after one of its engines suffered a catastrophic failure and rained parts of the engine casing in a neighborhood that narrowly missed a house.

The plane landed safely and no one on board or on the ground was reported injured, authorities said.

The Federal Aviation Administration said in a statement that the Boeing 777-200 returned to Denver International Airport shortly after takeoff after a right engine failure. Flight 328 was flying from Denver to Honolulu when the incident occurred, the agency said.

United said in a separate statement that there were 231 passengers and 10 crew members on board. The airline did not provide any further details.

The Broomfield Police Department posted photos on Twitter showing large, circular debris leaning against a house in the suburbs about 25 miles north of Denver. The police asked everyone who was injured to report.

Tyler Thal, who lives in the area, told The Associated Press that he was walking his family when he noticed a large airliner was flying unusually low and took out his cell phone to film it.

“As I was looking at it, I saw an explosion and then the cloud of smoke and some debris falling from it. It was like a speck in the sky and as I watch it I tell my family what I just saw and then we heard the explosion, ”he said in a phone interview. “The plane just kept going and we didn’t see it after that.”

Thal was relieved to learn later that the plane had landed safely.

The video posted on Twitter showed that the engine was completely on fire as the plane flew through the air.

Aviation safety experts said the plane appeared to have suffered an uncontrolled and catastrophic engine failure. Such an event is extremely rare and occurs when giant spinning disks in the engine suffer a failure and damage the armored casing around the engine that is designed to contain the damage, said John Cox, an aviation safety expert and retired airline pilot for an aviation safety consultancy called Safety Operating Systems.

“This unbalanced disk has a lot of power and rotates at several thousand revolutions per minute … and when you have that much centrifugal force it has to go somewhere,” he said in a telephone interview.

Pilots often practice how to deal with an event like this and would have instantly turned off anything flammable in the engine, including fuel and hydraulic fluid, with a single switch, Cox said.

Former National Transportation Safety Board chairman Jim Hall cited the incident as just one more example of “cracks in our aviation safety culture (that) need to be addressed.

Hall, who served on the board from 1994 to 2001, has criticized the FAA over the past decade as “a drift in letting manufacturers do aeronautical oversight that the public has paid for”. That is especially true of Boeing, he said.

Despite the scary appearance of a burning engine, most such incidents do not result in death, Cox said.

The most recent death on a US airline flight was an engine failure on a Southwest Airlines flight from New York to Dallas in April 2018. One passenger was killed when the engine disintegrated more than 30,000 feet over Pennsylvania and debris hit the aircraft and the window broke next to her seat. She was forced halfway out of the window before other passengers pulled her back inside.

In this case, the failure was attributed to a defective fan blade in a Boeing 737 engine. The Federal Aviation Administration ordered airlines to step up the inspection of fan blades on certain engines from CFM International, a joint venture between General Electric and France, Safran SA

In 2010, a Qantas Airbus A380 suffered a frightening engine failure shortly after taking off from Singapore. Shrapnel damaged critical systems in the aircraft, but the pilots landed safely. The incident was attributed to the incorrect manufacture of a pipe in the Rolls-Royce engine.

“The flames terrify everyone. But they are the least of a problem because you will put them out and turn off anything that can burn, ”said Cox.

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Associate press reporters David Koenig in Dallas and Frank Bajak in Boston contributed to this report.