A United Airlines plane

Nicolas Economou | NurPhoto | Getty Images

ON United Airlines Boeing The 777-200 heading for Honolulu suffered an engine failure shortly after taking off from Denver on Saturday, the Federal Aviation Administration said.

The plane returned to Denver, where it landed safely. Pictures shared on social media showed what appeared to be part of the engine cover outside a house while police shared pictures of other debris. United said no injuries were reported on board the flight.

“The FAA is aware of reports of debris near the aircraft’s flight path,” the agency said in a statement.

The plane left Denver International Airport shortly after 1:00 p.m. mountain time and returned to the airport less than 30 minutes later, according to flight tracking site Flightradar24.

The National Transportation Safety Board and the FAA said they are investigating the incident. The Broomfield Police Department in Colorado said the plane dropped debris in several neighborhoods and warned not to touch or move any part of the plane.

United Flight 328, a twin-engine wide-body Boeing 777, was carrying 231 passengers and 10 crew when the right engine failed, United said.

United said it is in contact with the FAA, NTSB as well as local law enforcement agencies about the flight.

“All passengers and crew were dropped off and transported back to the terminal,” United said in a statement in Denver. The airline said most of the passengers on the flight had been rebooked and en route to Honolulu on a different flight, while those who did not want to be rebooked on Saturday were given hotel stays.

“Extremely infrequent engine failures like this prove that there is no substitute for experience and that the most important aircraft safety system is two well-trained, highly skilled, professional pilots working on the controls on the flight deck,” said the Air Line Pilots Association union, which runs the Representing United pilots.

The Association of Flight Attendants-CWA, which represents United cabin crews, said its staff support and safety committees provide assistance to the crews.

“We are grateful that the plane landed safely,” said the union.

Boeing said it had received reports of the incident. Flightradar24 said the plane was powered by two Pratt and Whitney PW4000 engines. The Raytheon Technologies The device did not immediately respond to a request for comment.