Updated

Skywest Airlines says it's cooperating with an FBI investigation into an incident that happened overnight at a small airport in southern Utah.

Company officials say one of its aircraft was involved in an unspecified "ground incident" at the St. George Municipal Airport. They say the aircraft wasn't in service at the time, and the airport was closed.

St. George spokesman Mark Mortenson tells the Deseret News that all commercial flights have been cancelled until further notice, but the private portion of the airport remains open. The airport handles seven commercial flights a day.

Skywest says its passengers are having their itineraries rearranged.

Authorities didn't give details about the nature of the incident, but FBI spokeswoman Deborah Bertram says there's no ongoing public safety issue.

She says the FBI is conducting a joint investigation with St. George police and the Transportation Security Administration.