Fetus discovered inside empty airplane bathroom at New York's La Guardia airport

Investigators are trying to determine how the fetus ended up in the airplane.

American flight 1942 from Charlotte, North Carolina had arrived Monday night at 10:44 p.m. Passengers had long since disembarked by the time the plane was being serviced this morning. That’s when the cleaning crew found an under-developed fetus in a bathroom.

The plane was temporarily taken out of service while a forensic team from the New York City Office of the Chief Medical Examiner (OCME) spent several hours onboard.

"The OCME can confirm we're investigating what we believe to be a human fetus found deceased on an airplane," a spokesperson said in a statement.

There were no reported incidents during the flight, an airport source told ABC News.

A spokesperson for the Queens District Attorney Richard Brown, whose jurisdiction includes the airport, declined to comment.

"As we continue to learn more about this tragic and sensitive situation, we are working actively with law enforcement on the investigation."