Aviation officials say the main passenger door fell off a twin-jet business plane as it was taking off from a Colorado airport.

Federal Aviation Administration spokesman Mike Fergus says the door tumbled from the Bombardier Challenger CL-60 shortly after takeoff Monday from Grand Junction Regional Airport. No one was hurt.

He says that he doesn’t know how high the plane was, but that it returned to the airport and landed safely. He also didn’t know how many people were aboard, but the plane can seat about 20 passengers.

FAA investigators are expected at the airport Tuesday.

The plane’s registered owner is WFP Investments. No one answered the phone after business hours.