Watch: United Airlines Engine Explodes Mid-Flight; 'Immediately' Grounds 24 Planes For Safety Check

A United Airlines flight bound for Honolulu on Saturday suffered an engine failure mid-flight, causing debris to rain down on homes and yards in a Denver suburb.

United Airlines Flight 328 returned to the airport around 1:30 p.m. after it experienced right-engine failure shortly after takeoff. Some of the 241 people on the flight said they heard a “big boom” 20 minutes after the plane took off for Honolulu.

“There was a big boom and the kind of sound you don't want to hear when you're on the airplane,” Travis Loock, a passenger of the flight, told CNN. “And I instantly put my shade up, and I was pretty frightened to see that the, the engine on my side was missing. We were just glad we weren't over the ocean because that's where we were heading.”

Chad Schnell, another passenger, posted a video on Twitter showing the United Airlines plane’s engine on fire.

“Had a front row seat to the entire engine failure on United flight 328. Kinda traumatized to fly United more,” he wrote.

The pilots of Flight 328 issued a mayday call and turned back to the airport. They landed the Boeing 777-200 plane safely. None of the passengers or the crew suffered injuries.

United Airlines immediately grounded 24 of its Boeing 777 planes following the incident. The company is working with NTSB and FAA to conduct a safety check of its aircraft.

“Starting immediately and out of an abundance of caution, we are voluntarily and temporarily removing 24 Boeing 777 aircraft powered by Pratt & Whitney 4000 series engines from our schedules,” United Airlines wrote in a statement. “Safety remains our highest priority - for our employees and our customers.”

Footage and photos taken from the ground showed engine debris crashing to the ground in the Broomfield neighborhood. The large circular covering to the jet engine fell next to Kirby Klements’ home. His house did not sustain serious damage.

Mark Moskovics, a homeowner in Broomfield, captured a video of the engine debris crashing to the ground. In an interview with KCNC, Moskovics said he heard a loud boom and looked outside to see a large piece of debris falling from the sky.

"So then I went upstairs to get my wife and baby who were napping upstairs and have them come down and make sure they were safe," he said.