Two Hawaiian Airlines passengers were detained by federal authorities Wednesday after behaving suspiciously on a flight to Seoul that was forced to return to the islands.

Hawaiian Flight 459 left Honolulu Airport at 2:45 p.m. with 286 passengers.

In a statement, Hawaiian said the aircraft returned at 8:35 p.m. after flight attendants reported suspicious behavior by a passenger about three hours into the flight.

The plane was met by FBI agents after landing safely at the airport.

Two passengers were briefly detained and questioned by FBI officials but later released. After interviewing witnesses and inspecting the plane and its contents, the FBI said it determined it was safe.

“Our investigation indicates that the incident in question was not an intentional threat to the crew or passengers onboard the plane,” said Matthew McDonald, FBI supervisory special agent. No charges are expected to be filed.

FBI officials would not disclose specific details about the incident.

The remaining 284 passengers departed for South Korea on a different Hawaiian Airlines aircraft at about 12:30 Thursday morning.