A passenger plane has skidded past the landing strip and overturned in the eastern Ukrainian city of Donetsk, killing four people.
Two others were injured and the fate of two more is unknown, officials said.
The small, Soviet-designed AN-24 plane was carrying 45 people from the Black Sea port of Odessa.
It was not immediately clear what caused the crash-landing, emergency situations ministry spokeswoman Inna Sedova said.
The plane was operated by the small Southern Airlines company, which runs domestic flights out of Odessa.
Donetsk governor Andrei Shishatsky said that rescuers had located one of the missing people in the wreckage of the plane but were still unsure whether the person was alive, the Interfax news agency reported.