A passenger opened a door on an Asiana Airlines flight that later landed safely at a South Korean airport, officials have said.
Some people on board tried to stop the person from opening the door but it was eventually opened partially, the transport ministry said.
The plane, with 194 people on board, was heading to the south-eastern city of Daegu from the southern island of Jeju on Friday.
Police detained the unidentified person who opened the door, the airline said. Their motive was not immediately known.
The passengers included teenage athletes who plan to attend track and field competitions in Ulsan, another south-eastern city.
The incident terrified some passengers but no-one was injured, though some passengers were assessed at a hospital, Asiana and government officials said.