Photo taken on Oct. 8, 2012 shows the terminal building of Gansu Zhongchuan Airport in Lanzhou, northwest China's Gansu Province. A passenger plane made a forced landing in Lanzhou on Monday afternoon after receiving an anonymous "terrorist threat," local security authorities confirmed. The plane landed at Gansu Zhongchuan Airport at around 5:30 p.m., according to sources with the airport and the local provincial government. All people onboard were evacuated by 5:45 p.m., the sources said.