The Boeing 757 was headed from Denver to Los Angeles on Sunday when one of its two engines shut down shortly after take-off.
The plane with 125 people on board was forced to land in Grand Junction, Colo.
Some passengers said they smelled smoke and gasoline before the plane took off. Minutes into the flight, the pilot made the announcement.
"The pilot came on and said...the engine had an oil malfunction of some kind so we've shut it down, and we're going to divert to Grand Junction," said passenger Alex Sklarevski.
Another plane took the passengers to Los Angeles.
No injuries were reported. The cause of the engine problem remains under investigation.