Beijing ( CNN ) -- Three Chinese airlines received `` false bomb threats '' on Wednesday that caused disruption to five different domestic flights destined for the southern city of Shenzhen , state-run media reported . Shenzhen Airlines said on its official microblog account that it had received multiple threats that lead it to reroute two flights and delay another . A flight to Shenzhen operated by Juneyao Airlines returned to Shanghai , its point of departure , so that the plane , passengers and baggage could all be checked following a threat , the state-run news agency Xinhua reported . The flight eventually took off using a different plane , the news agency said . China Eastern Airlines received a threat regarding its flight from the northern city of Lanzhou to Shenzhen , via the central city of Xi'an , Xinhua reported . The flight was subsequently cleared for takeoff , it said . According to China Eastern 's website , the flight 's departure from Xi'an to Shenzhen was delayed by more than two hours . Shenzhen Airlines said that a flight from the eastern city of Nanjing returned to its point of departure , a flight from Xi'an changed course to land in the southwestern city of Guilin , and a flight from Beijing departed late after police talked to passengers . Police are now investigating the case , according to Xinhua and Shenzhen Airlines . Asked for further comment on the threats , Shenzhen Airlines directed inquiries to the individual airports where the threats were received . CNN 's Feng Ke contributed to this report .
NEW : Police are investigating the threats to three Chinese airlines . Five different flights to the southern city of Shenzhen are affected . Two flights are rerouted and three are delayed . The state-run news agency says the airlines received `` false bomb threats ''