Agence France-Presse is reporting that a Ukrainian airliner made an emergency landing in Turkey due to a hijacking attempt: 

Other reporters are adding details on Twitter. So far, they've said that the Pegasus plane contains 110 passengers, and that the hijacker attempted to divert the plane to land in Sochi during the Winter Olympics opening ceremony. One passenger reportedly shouted that there was a bomb on board. A Russian reporter and others have said the hijacker has been 'neutralized', and  Turkish state media notes that the plane is now at a safe zone in a Turkish airport.

Turkey's Hurriyet Daily News  reported that an F-16 military jet forced the plane to land in Turkey following the hijacking attempts. This is a developing story. 

Update: According to the Associated Press the 110 passengers are still on board the plane, which is currently on the ground at Sabiha Gokcen airport in Istanbul. Habib Soluk, Turkey's Transport Military undersecretary, told Turkish news channel NTV that officials are trying to convince the hijacker to turn himself in. The Telegraph reports that Soluk said "We are sure that he didn't enter the cockpit. We know that the aircraft was hijacked before it entered Turkish airspace." 

Reuters reports that one airport official said "people are still inside but the pilot called security and gave them a signal that they can enter the plane. There is a translator -- a Turkish man near the Ukrainian to calm him down."

According to Reuters, Turkey's Dogan News Agency reports that "the passenger was believed to have drunk alcohol and was calmed down by the crew and persuaded to let the plane, a Boeing 737-800, land in Istanbul at 6:02 pm." 

The New York Times adds that, per CNNTurk, the crew convinced the hijacker that the plane had landed in Sochi. The Wall Street Journal has more details, including that the hijacker was reportedly "heavily drunk," 

Ukrainian Deputy Foreign Minister Vasyl Zvarych said the alleged hijacker is a Ukrainian citizen born in 1969. The Ukrainian consul is at the airport in Turkey to help Ukrainian citizens who were on board, he said.... A representative for the [Ukrainian security service] SBU said in a statement that the passenger was "heavily drunk," according to the Interfax news agency. "He tried to enter the pilot's cabin, calling out, "Let's fly to Sochi," the representative said, according to Interfax.

According to the representative, the passenger was not armed.