(CBS News) -- Federal investigators are trying to find out why a cargo plane lost a landing gear door in mid-flight.
The door, nearly the size of a refrigerator, crashed onto a quiet street outside Seattle and residents are asking a lot of questions.
No one was killed or seriously injured, despite the timing of the incident, in the early morning just as children were heading to school.
Photo Gallery:Door drops off jet, rattles Seattle suburb
At around 7 a.m. Friday, Kent, Wash. residents saw a cargo plane flying low overhead.
"It sounded a little [as if], maybe, it was distressed. Yes, distressed or vibrating or whatever," resident Diane Oien recalls.
Moments later, witnesses say, the door plummeted from the sky and skidded 30 feet along the ground before finally coming to a stop in front of a house.
"We were grateful no children were hurt and it didn't hit a house or a car," says resident Maureen Rinabarger.
But for the house's owner, it was a close call.
"I pulled out, [was] gone about five minutes, came back, and there's an airplane part sitting in the driveway," says John Hansen.
The Federal Aviation Administration says the door belonged to a Boeing 767, but will not release any other details before their pending investigation.
"All I know is that an aircraft passing overhead lost a part, and we were called out to identify it and take it away," says the FAA's Ron Zibbler.
"CBS This Morning" has learned the door belonged to an ABX Air cargo plane flying under the DHL logo. It was en route from Cincinnati for Seattle's Boeing field.
ABX operates many flights for DHL, the shipping company.
"This aircraft was built in the early '80s, delivered, had a number of cycles on it -- landings and takeoffs -- lots of maintenance activities occurred," points out CBS News aviation analyst Mark Rosenker.
The door landed less than 50 miles from where Boeing builds its planes.
It's just the latest in-flight incident involving Boeing jets.
In May, an Air Canada Boeing 777 bound for Japan suffered engine trouble and rained engine parts on a Toronto suburb shortly after takeoff.
And in July, a Boeing 787 Dreamliner undergoing testing sprayed hot engine parts on a runway in Charleston, S.C., igniting a grassfire and briefly shutting down the city's airport.
"These are such rare occurrences," Rosenker observes. "These aircraft are built extremely well. [They have]high- reliability."
But for Ken residents, that's little comfort.
"I just assumed that the parts stay on the plane. You know -- it is a little nerve-wracking," Hansen says.
ABX told CBS News it has a rigorous maintenance program and had no prior history of incidents of this type.
Boeing says it's prepared to offer any assistance with the investigation, but has yet to be asked for any by federal authorities.